The concept of sacraments is central for Catholics and Orthodoxes, however their praxis is usually criticized by Protestants. It is probably the last opportunity when the Messianic Judaism could finally solve this controversy without fetishisised terms.
A sacrament is G-d's instituted / ordained Mystical Sign which presumes further G-d's Gift of Grace. This Sign is given to a believer as G-d's answer to believer's faith in full accordance with G-d's and believer's mutual will. The Sign shows that a believer really has a chance to receive G-d's answer which nevertheless is not granted automatically. In other words, the Sign does not bind G-d anyway. No human action can lay G-d under obligation to respond in accordance with human will, or even to respond at all. Otherwise one had a kind of wild chamanism. However sacrament is a real Sign which grants a hope of following Grace according to the Word of G-d Himself.
G-d Himself ordained sacrificial actions of the Kōhēn (Elder Priest, i.e. descendant of Aharon in the tribe of
Levy) in yt hamMiqdāš (the Temple). Most of these actions were necessary for a sacrificer (a person offering a sacrifice) to obtain Grace of abolition of his concrete sin. However this does not mean G-d had “no righ” to reject the offering.

However the sacrifice itself is much older than yt hamMiqdāš: cf. stories about offerings of Abel and Cain (Gen = BəRēšīt 4, 3–4 f.). When Abraham asks G-d “Whereby shall I know that I shall inherit it [the country]?, G-d answers with only a commandment “Take me a heifer of three years old, and a she goat of three years old, and a ram of three years old, and a turtledove, and a young pingeon“, however Abraham fully understood everything and knows what was to do (Gen = BəRēšīt 15, 8 f.). Why? Only because a sacrifice had already been very well known to him as a form of covenant. Even more: it was a well-known form of covenant in the whole primitive world. Sides (e.g. several tribes) entered a contract through sacrificing animals which were torn in parts according to the number of sides (chiefs of tribes, as well as their deities as whitnesses of the covenant, of course). The sides had to pass through divided pieces, and after that each of them ate own part. Cf. relics of the same root in akin archaic languages: Lithuanian deru ‘I bargain for’, diriu ‘I skin (a skin)’ and Gr. δέρω ‘I tear, skin’, Lithuanian darna ‘harmony, concord’ and Russian dranj ‘torn pieces’, Lithuanian derybos ‘negatiations’ and Latvian Derība ‘Covenant’. Cf. above mentioned narration about Abraham's sacrifice: “When the sun went down, and it was dark, behold A SMOKING FURNACE, AND A BURNING LAMP THAT PASSED BETWEEN THOSE PIECES. In the same day the L-rd made a Covenant with Abraham” (Gen = BəRēšīt 15:17–18).
When making Covenant with Abraham, G-d followed a way widely known in the whole archaic world of that time. To enter a covenant means to cut a covenant in Hebrew. Cutting of a victim and partition of its pieces among participants of the covenant means that in case of trespassing the terms, each side agrees to be torn similarly to the animal sacrificed, cf. BəRēšīt 15, 8 and Jer = Yirməjāhū 34:18: “And I will give [to enemies] the men that have transgressed My Covenant, who have not performed the words of the Covenant which they had made [“cut ”] before Me, when they CUT THE CALF IN TWAIN AND PASSED BETWEEN THE PARTS THEREOF”. The latter passage from Hebrew Bible is often presented as in a Syrian version (cf. NIV, ESV etc.): “Those who have violated My Covenant and have not fulfilled the terms of the Covenant they made before Me, I will treat like the calf they cut in two and then walked between its pieces”. 

Thus something sacrificed and eaten seals the covenant. A person who trespassed the Covenant of Sinai with a sin automatically dropped out of the Covenant. He could come back into the Covenant by ordinary sacrifice, first having confessed his sin. Circumcision became an everlasting sign of the seal of the Covenant between G-d and Abraham (BəRēšīt 17:2–14). A following Covenant between G-d and Jews, descendants of Abraham’s son Yitshak, was concluded at mount Sinai through the mediation of Moshe (Moses) when the Law was proclaimed to the people and when the people concented to it (Ex = Šəmōt 19 – 24:3). This Covenant was confirmed with a sacrifice too (Šəmōt 24:3–8). From that time sacrifices became a statutory sign of confirming the Covenant: a person (or baby) entered the Covenant through circumcision, but any time he fell away from it through sinning (when adult), he was able to come back through a sacrifice, i.e. by renewal of the Covenant. In both cases, whether it was Abraham’s Covenant, or Sinai Covenant, members of the Covenant (G-d, His priest or/and a person) ate own parts of he sacrificed (G-d “ate” with fire). This action guaranteed keeping to the Covenant.  

The Lord Y-shua made Himself a Matter and Seal of the New Covenant between G-d and His people. During the Last Supper He ordained repetition of His Sacrifice (which replaced all previous sacrifices of the Sinai Covenant) in His remembrance. Being sacrificed once and for ever, He made an eternal Sign of His sacrificed Body to be eaten any time in form of Bread as a seal of the New Covenant. Bread is broken (sacrificed) and eaten confirming entering the New Covenant, being in it, coming back in it, as well as uniting all believers in His Sacrificial Body, which is His eternal Church. 
This Sign appeared from a well-known form of blessings of wine and bread by every Jew at every Sabbath and every festival. 

However it is namely eating of bread during Sabbaths and festivals, or namely eating of own part of the sacrifice once in the Temple. Wine is also drunk during Sabbaths and festivals, however blood has been never drunk nowhere, neither in the Temple, of course. Blood was spilt out in the Temple, or people were besprinkled with it (cf. a purifying blessing of people with the words “His Bood on us, and on our children!” in Matth 27:25). Here one faces a problem: how could Y-shua say to His disciples “Drink, this is My Blood!” when G-d and His Law strictly prohibited to eat (drink) blood? – Gen 9:4, Lev 3:17, 7:26, 17:10–12, Deut 12:16,23. Did Y-shua really overturn the Law upside-down while being G-d? Has G-d divided against Himself?
Had it been his disciples, who did not dare to inquire Him after the sense of His words, should He not but understand their astonishment as Jewish-grown people and explain to them why He was breaking the Law in spite of His own words that He had come to fulfil, not to break it, from which neither jot, nor tittle would pass till (‘έως ’̀αν) all be fulfilled (Matth 5:18, “all” meaning His final coming in glory? or not?)?
A suspicion arises that the second part of the Eucharist formula got into traditional Masses in a distorted form, a corresponding place in Matth 26:27–28 having been changed according to Matth 26:26 by Greek copyists.
Here it is: this part of the formula presented in Luke 22:20 and in 1 Corinth 11:25 differs essentially from that in Matth 26:27–28! 
Luke: “This Cup is the New Covenant in my Blood, which is shed for you” – no problem for a Jewish-grown person!
1 Corinth 11:25 adds to this: “This do ye, as oft as ye drink, in remembrance of Me”.
Mark 14:23–24 even changes the sequence:  “He took the cup, and when He had given thanks, He gave to them: AND THEY ALL DRUNK OF IT. AND HE SAID TO THEM ...” – further the words from Matth 26:28 are repeated.
It has been stated during last 50 years that the original language of the Gospel to Matthew was Hebrew, not Aramaic(
Grintz J.M. Hebrew as the spoken and written language in the last days of the Second Temple. / Journal of Biblical Literature 79, March 1980, Part 1, p. 32–47), however the Gospel to Mark was a subsequent shortened Aramaic translation (targum) of Matthew's text, read in assembleys for those who did not understand Hebrew (Грилихес Л. Реконструкция коммуникативной ситуации создания и первоначального функционирования первых двух канонических Евангелий. Кафедра библеистики МДА, Москва 2005).
If the second part of the Eucharist formula is authentic in Luke 22:20 and in 1 Corith 11:25, then it becomes clear that Y-shua spoke about the Cup of His Suffering to be drunk by Him, the New Covenant coming into being.
One finds image of a coming suffering as of a cup to be drunk, in Y-shua's prayer in the garden of Gethsemane: “Father, if it be possible, let this Cup pass from Me” (Matth 26:39), as well as in His words addressed to Zebedee's sons: “Are ye able to drink of the Cup that I shall drink? /.../ Ye shall drink indeed of My Cup” (Matth 20:22–23).
One says nothing new if asserts that the Gospels underwent a strong “editing” by Greek Copyists. For them, as descendants of the Pagans, “drinking blood” could not be associated with any prohibitions. Furthermore, there existed ethnical hatred and bloody conflicts between Greeks colonists and Jews, starting from the Kitos War (115–117) up to coming of Moslems to Palestine in the 7
th c. This caused a kind of Anti-Semitic ideological editing in turn. Cf. e.g. a putative interpolation 1Thess 2:15, not to say about Anti-Jewish editing of the latest Gospel to Johannan (John). The word Jews in this Gospel has a dominant negative connotation to such a degree that any ignorant person in no way perceives that JHS, or His disciples, can be Jews! Cf. “a question between John's disciples and the Jews” (Jn 3:25), or an apparently absurd statement put (in accordance with Matth 15:2, with all probability) into Y-shua's mouth by some Greek obscurant in Jn 7:22 (for this see Gen 17:10-11,23,24, 21:4, Ex 4:24-26, 12:4344,48, Lev 12:3!)
Therefore, one cannot be sure whether the words drinketh My Blood added to “Whoso eateth My Flesh” in Jn 6:54,56 were authentic. Y-shua's words with no doubts emphasize the single truth that in Him survive only those who live at the expence of His Sacrificed Life (it was quite natural that this sense appeared to be an allleged blame for a number of His disciples – “This is a hard saying; who can hear it?” – and they seceded, Jn 6:60).
All the more, there coud not be even but surmised any difference between ‘Eat, this is My Flesh” and “Drink, this is My Blood” in an official new Non-Jewish Church established in Nicea in 325, Matth 26:27–28 having been coined after Matth 26:26 by Greek copyists in a much earlier epoch. This unimaginable coinage became anchored in the Masses for ever.
Add to this that the sense of making a covenant through a sacrifice had been already faded in comprehension of the Jews themselves in the 1
st c.: Hebr 9:13-14 does not emphasize power of Y-shua as Subject of the Newtestamental Sacrifice, but intellectualize on much more greater power of His Blood than that of calves and goats... 
The shift in sacrificial covenant from one to another explains in turn, why Y-shua Himself, being Messiah and the High Priest, is our Temple at the same time. 
In order to interpose ourselves with our miserable offering into His Cosmic Covenant we should be present in His Sacrificial Body. If this happens and our miserable offering becomes embedded into His Golgotha Sacrifice, then He Himself is present in us. A person as a member of His Mystical Sacrificed Body, becomes a little messiah
redeemer for other people [a wonder, there is only one word Christ for Y-shua and for a Christian in the German language!]: “I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me” (Gal=GālāTijjīm 2, 20).
When we are witnessing this publicly in remembrance of His Last Supper, G-d makes us participants of the Last Supper with all Grace in accordance with His Mystical Sign of the Blessed Sacrament. For His sacrificed Himself historically only once, however in order His Body should be sacrificed always, every generation must enter the Covenant, every person entering and fixing oneself in it, and coming back into it after any transgression many times. Therefore the ratifying of the Covenant by eating own part of the Sacrifice is eating of the Mystical Sign, what can be named Sacrificial Christ. With it
a New Covenant keeps to be further confirmed, once concluded on Golgotha Cross between G-d and His Chosen People (Yirməjāhū 31:31–32), into Which the whole world is being invited today (Gen 12:3, Isaiah 11:10, Rev 6:4–17).
This is why Eucharist exists in all Christian denominations in spite of its different comprehension there even 2000 years after Golgotha having passed away.
Nevertheless even during traditional halachian Jewish Pesah party, a piece of unleavened bread, named Afikoman, broken and divided among participants of the party after the Second cup of wine, is a mystical equivalent of sacrificed Flesh of Messiah. However a Messianic believer renews his Covenant with G-d through the Sacrifice of Messiah when having eaten his part of the Afikoman. In this way a believer becomes participant of the Sacrifice, while all participants together once again join in the Church, i.e. in the Sacrificed Mystical Body of Messiah. The Third Cup of Pesah, the Cup of Redemption, is a Sign of the Cup of Suffering drunk by Y-shua on the Cross of Golgotha. Therefore He identifies this Cup with the New Covenant in the shed Blood of the Lamb, i.e of Himself. Similarly as a believer does not eat meat of Y-shua when eating the Afikoman, so he drinks not the physical Blood of Y-shua when drinking the Third Cup, however he drinks from the Cup of Suffering, the Sacrificed Blood of Y-shua being shed on Golgotha, and obtains eternal life. 
This means that a person unites oneself with the Flesh and Blood of Y-shua only with greater or lesser personal sacrifice in own practical real life (“I am crucified with Christ“ Gal=GālāTijjīm 2, 20), but the Mistical Sign of the Blessed Sacrament confirms this Grace none the less than the Sign of Qorbān ‘Ōlā (Burning Offering) confirmed G-d's Grace in Bēt ha
mMiqdāš (the Temple). The Power of G-d performs in me a change promised with G-d-donated Mystical Sign, if (if!) G-d accepts the offering and (if!) I do not approach the Holy Communion unworthily. Otherwise there should not have been an admonition “he that eateth and drinketh unworthily, eateth and drinketh damnation to himself” (1 Kor=Qōrintijjīm ālep 11, 29).
One could not approuch sacrifices of the Sinai Covenant if having a sin (one had to confess own sins before the offering). The same is in the New Covenant, when we really are Y-shua's “bloodsuckers” as living at nthe expense of His Sacrifice. One must aknowledge this differently from those disciples who ran away in fright of this truth (
Jn 6:60)

The Covenant in the Blood of Y-shua is a Covenant of constant possibility of Salvation for everybody, when the Saviour, Who fulfills the Law in His Ecclesiastical Body, at any moment abolishes the sin of those who performed it because of practical impossibility of a man not to transpass the Law which is perfect in its holiness. 

Our correspondent, a traditional Jew, says that the Blessed Sacrament seems him to be a classic sample of occult sorcery, when a person creates for himself a demon, but the demon demands offerings in order to maintain own existence and to nurture the growth of its force. 
In reality, Y-shua is mentioned as a sorcerer in Talmud (
Sanhedrin 43a, see Gemara 33 f.) Putting aside other negative expressions about Y-shua in Talmud, which is a collection of various opinions of Rabbis, one should recognize that opinions of any opposing religious stream cannot be positive in principle. E.g. almost all new Protestants (since the 19th c.) name Catholic Church Whore of Babylon, but the Pope - apocalyptic Beast and Antichrist. Accusing Y-shua of sorcery is as old as His preaching, cf.“The Jews answered him, Aren’t we right in saying that you are a Samaritan and demon-possessed?“ (Jn=Yōhānān 8, 48). In addition, the“Christians“ themselves strongly contributed to Jewish negative opinions due to centuries of persecutions. Cf. mostly rigorous reaction in Shulkhan Arukh, the 16th c., which equates the akum's (“worshippers of stars and planets“, i.e. non-Jews, practically Christians in Europe) to animals what is quite fair after all savage persecutions. Facing the historical fact of these “Christian” persecutions, any traditional Jewish doctrine of any higher soul does not matter. 
However this is not our case. If one rejects Incarnation and Divine origin of Y-shua in principle, then it should be only logical to consider being occult all sacrifices related to Y-shua. G-d prohibits to worship and to maintain with offerings any demonic force: the worship belongs to G-d only but the offerings remunerate His Justice. It is difficult, if possible at all, to comprehend Redemption if not believing in the Divinity of Y-shua. Therefore, formulas of the Necene-Constantinople Credo of 325 / 381 are the only mental means to most roughly explain the faith, how hopelessly they may not but be far from the higher reality, incomprehensible to human mind. Therefore, one accepts this faith under the impact of the Holy Spirit alone, without any real comprehension. Dostoyevsky wrote it would have been impossible for him to live without Redeemer, the redemption being existential necessity able to morally justify life in the world of sinful humans. Despite Antisemitism, which was a result of his attempts to replace Divine Messianism of the Jews with mentally-pagan chauvinist “messianism” of the Russians, Dostoyevsky has expressed a messianic truth of the preeminence of the Divine morality without which the traditional rabbinic way toward nearing messianic era is possibly an impasse.  
Taking a risk to leave Redemption without explanation (how a man can redeem the mankind from its guilt against G-d?), one maybe could evade the question of Y-shua's Divinity due to incomprehensible character of Incarnation and Trinity, however it is impossible to evade the Cup of Suffering without rejecting the Gospel. 
Golgotha Sacrifice makes sense of the Gospel. Without this Atoning Sacrifice the Gospel becomes a kind of fabulous Moslem “Injil”: what then does Islam consider to be a genuine“undistorted“ Gospel (Injil) and Christianity? What is the difference between Prophet Y-shua and Prophet Elias? Why should one speak about Christianity but not about “Elianity”? What is the distinctive feature of that primeval “undistorted” (yet not distorted by the Christians) Christianity and the sense of it? 
These are questions to Moslems, because Christianity without Redemption seems to be unnecessary, it remains a sect of traditional Judaism, or with an addition of Prophet Muhammad (i.e. on going out from the Jews into a broader world), it turns into Islam and vapours away. 
Fortunately the Quran often mentions Christians, not only “distorted” but also “yet undistorted” (of what time?) who are even presented (in Prophet's time?) as samples of the absence of loftiness
(Qur’ān 5
:82). Islam cannot be evaded with any tricks, it cannot be pushed aside or kept silent, not only because of Torah foretelling its significance in the last days (Bərēšīt 16:12). It cannot be evaded as a powerful Abrahamic witness of Y-shua being Messiah exactly in Judaic context (Qur’ān 4:157) exactly!
Turning back to the Holy Scripture, one finds a woderfully precise prophetic description of the Golgotha Sacrifice in
Isaiah (
šà‘yā) 53, i.e. long before Golgotha. In addition, there is almost a dogmic delivery of the "Divinity" (unity of G-d Farther and Son) in the New Testament in many places of the Gospel of Yohannan (John) as well as in Paul's epistles, if not really of the Trinity in usually questioned places Mt 28, 19 and 1 Jn 5, 7 (interpolations argued but cf. the most intriguing place in Torah: Gen=Bərēšīt 18 !). 
Besides that, the story of the Cup of the Last Supper in 1 Cor 11 is an indubitable authentic text
coming from the 1st c. A.D. still before the ruination of the Temple, according to modern textual criticism.