1.  Definition
2. “Theory of Replacement”
3. History

Faith is the assurance of things hoped for, the conviction of things not seen.
(Hebr=‘ibrîm 11, 1)


1. Messianic Judaism is a faith and movement of the Chosen Jewish people, who have accepted the L-rd JHS as Messiah (Hebr. Mađîah="anointed one"=Christ from Gr. Χριστός “anointed one”) and Saviour of the world.
Messiah's name is
a (-- = çđ), however the vowel a is not a part of the original Name! (read special explanation)  This name got into world languages first through Greek. There was no consonant sh [đ] in Greek but the long vowel ç was transformed into i there at time of the borrowing. From Greek the Name spread further through the mediation of Latin. In Latin the pronunciation of Greek s turned into z between vowels, however former ç continued to be rendered as e. Therefore one finally got J-sus in English with its initial J- from Latin written J- pronounced Y- (in Latin). Jewish Tetragrammaton is consedered to be holy and non-pronounceable as a forbidden to utter Name of G-d. Neverthe less G-d did not say His Name to Moshe (Moses, Ex=Shemot 3:14). A Name of Messiah shown to mankind should be especcialy holy in turn (see Acts=Ma‘asç 4:12), therefore it should be protected from any attempt of desacralization by people of bad will. Therefore this Name is not written on this site in its fyull form, thus broadening the said Jewish tradition.

G-d has chosen His people for the Messiah when He marked them out from all nations of the world, in accordance with His promise to Abraham (Gen=Berçđît “in the beginning” 17:21). The Jews is a nation with which G-d established His Covenant first at Mount Sinai, where He announced His Law (Torah) to His people, but after that He established His New Covenent (Jer=Yirmejâ-- 31:30-33), Berît Hadâđâ, with them, and with other peoples through them, in Blood of JHS's Sacrifice on Golgotha Cross (Hebr=‘ibrîm 8, 6-13).

Thus the word “messianic” (“belonging to Annointed”, from original Hebrew sourse) appears to be synonymous to the word “Christian” (“belonging to Annointed”, from intermediate Greek source), although the historical use of both differs. Despite being Judaism of the New Covenent, Christianity lost remembrance of its Jewish roots among christianised Gentiles. There are lots of them without any idea of J-sus Christ definition as a confession that JHS is Messiah (cf. Mt=Mattâj 16:16), however many of them consider this to be a name and a surname of the L-rd... This is in spite the fact that the traditional Christians (better to say traditional Christianity), as well as the Messianic Jews, and even the Moslems, are awaiting His coming. The halachic Jews (Jews of most spread Halachah tradition of the ‘Oral Torah’) are waiting for Messiah too, however they do not believe yet that JHS is the Messiah. In addition, many traditional Christians are ignorant of apostle Paul's remark on their being grafted onto the roots of the Chosen people through the faith in JHS. In any case it was not “the whole mankind” with which the New Covenant was established. It was not established neither with the Koreans, nor with the Eskimos. The New Covenant was first established with the Jews (Jer=Yirmejâ-- 31:30-33) chosen for this aim only. All the others have only been grafted onto the Jewish roots (Rom=Rômijjîm 11:17-20) in order to become part of the Chosen people, not differentiating inside them (Col=Qôlassijjîm 3:11)
Thus the New Covenant has been established with the Jewish people in Atoning Sacrifice of Messiah JHS. Sacrifices of thr previous Covenant abolished, it has been established “with many” too
(Dan=Dânijjçl 9:27).

2. Therefore, the Messianic movement reminds that the Jews are a nation of JHS, His Mother, apostles and the first Christians. The Body of JHS Messiah is the Body of the Chosen Yiúrâ’çl (Israel) people. The Church unites all faithful believers into the Sacrificed Body of Messiah, and is mystically identical with this Body. Therefore the Church is the Chosen people consequently. No doubt, according to the Grace of Salvation for everyone equally, there are “neither Jew, nor Greek” inside the Church (Col=Qôlassijjîm 3:11), all members of the Church constituting the same Chosen people. An inadequate understanding of Col=Qôlassijjîm 3:11 was an indirect reason why misinformed people believed for centuries in replacement of the Jewish people, as Chosen people, with christianised pagans: say, no difference between the Jews and the Gentiles existed for G-d, but He ostensibly chose... “Christians” instead of the “Jews” for the sake of the “replacement”! 
Although the II Vatican Council removed this tautologic mistake and the Catholic Church rejected the ‘Theory of Replacement’, this has had almost no impact on old oriental churches, as e.g. on Orthodox churches. On the other hand, there appeared an opposite tendency in the Catholic Church to speak about some separate way of the halachian Judaism which ostensibly needs no faith in JHS Messiah as Saviour of the Mankind. 
However the Messianic Judaism is a proof of both: JHS is Messiah prophecized by the Jewish prophets, but the Jews remain being Chosen people who have not rejected JHS as a people. Fulfilment of the times of the Gentiles having started and the Jews having regained
erűđâlayim (Jerusalem) in 1967 in accordance with Lk=Lűqâs 21, 24, rebirth of the first Christian Church of Ya‘ab (Jacob) began: there are ca. 50000 Messianic Jews in almost all towns in Yiúrâ’çl today, and ca. a quarter of one million all over the world. 
This, as well as the prophesied return of the Jews to the Promised Land
hezqçl 36, 24-28), are important signs of the final (apocalyptical) days. Traditional Christian world turning back to paganism, the Messianic Jews show the fount of our faith being still pure, and this encourages the last faithful Christians to unite themselves round this fount. One should remember not only that “the gates of hell shall not prevail against the Church” (Mt=Mattâj 16:18), but that “all Israel shall be saved” (Rom=Rômijjîm 11:26) either. We do not know yet which of today traditional Christian denominations survives, and whether any of them survives, till the final day (Lk=Lűqâs 18:8), however we know undoubtedly that the remnant of Israel, which will have come back to the Promised Land (Iz=Yeđà‘ja 10:22), will be the Church Body of JHS. No doubt, JHS's Salvatory Sacrifice did not revoke His Own words “salvation is of the Jews” said to a Samarian woman (Jn=Yôhânân 4:22) in spite of any desire of any kind of Anti-Semites who have already “abolished” G-d in their erstwhile Christian countries.

3. Messianic faith is apostolic and essentially pre-Nicene in spite of any dogmic diversity among the Messianic Jews today. Messianic Jews withered away for a short while of ca. 1600 years (what do 2000 years mean for G-d?), especially after Emperor Constantin had initiated the 1st Church Council in Nicea in 325. In his letter to the council the Emperor cursed the Jewish nation (cf. Gen=Berçđît 12:3!) as a Deicidal one. 
The Emperor convened the Council in order to condemn Arianism, however he himself adopted baptism from an Arianic bishop later, what shows him having no comprehension of theology. Therefore
his friend bishop Eusebius of Caesarea seems to have inspired a letter which names the Jews Deiciders and “polluted wretches”: “... in the first place, it seemed to every one a most unworthy thing that we should follow the custom of the Jews in the celebration of this most holy solemnity, who polluted, wretches! having stained their hands with a nefarious crime, are justly blinded in their minds. /.../ it belongs to your ready discernent, both by diligence and prayer, to use every means, that the purity of your minds may not be affected by a conformity in any thing with the customs of the vilest of mankind. /.../ we may have nothing in common with the usage of these parricides and murderers of our Lord.” This is not only a starting point for the “theory of the replacement” of Jews by the Gentiles in the Church. This is also a crime of the replacement of the first Apostolic Church with a Gentile Church, possibly falsified by Eusebius himself. In his “History of the Church” he names 15 Jewish bichops of Jerusalem before its ruination, but there were tens of thousands Jewish Christians in Palestine at that time. All of them were exterminated by the Romans together with traditional Jews as rebels, but Eusebius mentions rebels as having got “deserved punishment”, similarly as Jerusalem having been renamed to Aelia (consecrated to a pagan devil, what a “brilliant Christianity”!) However those rebels did the same as Maccabees, why did Eusebius use a double standard? Was this because of his pro-Roman position? In other words, Eusebius persuades the emperor: these were they, cursed Jews, real enemies of the Empire, who rebelled, not we, loyal Greek and Roman Christians! It is not comprehensible why did he make an exception for Y-shua Himself, His Mother, His disciples at all, plus a few dozen persons more: were they Jews, or not?
It looks like a new Church arose at the expense of authentic first Christian Church expelled and dispersed by the pagan Roman army. The new Church of the Gentiles negated the first Church, eradicated even a remembrance of it and identified it with the whole Jewish nation which ostensibly repudiated their Messiah unanimously and became a nation of deiciders. In doing so, the Nicene Church profited in ascribing to itself all labour of the previous Church and in getting rid of any competitioner as well as of all Old Terstament prophecies, now declared to have been revoked. Further in his History, Eusebius mentions Ebionites as some weak-minded Jewish sect, although there remained many thousands of very different Jewish Christians under this name up to at least the 7th c., fully pushed aside by newly created Gentile Church, while the Jewish Christians were doomed to disappear mostly among Syrian Christians and this was end of the first followers of Christ, of the Church of Jacob and Peter-Kepha! 
Bloody ethnic conflicts between Jews and Pagan Greeks erupted during Judean wars, especially during the Kitos war (115–117). Pagans of the Roman Empire began to perceive Jews as enemies. Those of them who had accepted Christianity, began to quickly alienate from the Jews and did not want to be counted Jewish by Roman authorities: this was especially dangerous, because Roman authorities persecuted them for refusal to offer pagan sacrifices, a reason of the Jewish war itself.  Gentile Christians in Rome and Alexandria avoided to assemble on Sabbaths in order not to be confused with the Jews. They only wanted persecutions to be stopped and they could live as patriots of the Empire. Any memory of once numerous first Jewish Church could only hinder them in their rejection of compromising “Jewish customs” (i.e. of G-d commandments in Torah), because the very this rejection, in turn, was grounded in ostensible rejection of Christ by the whole Jewish nation. 
This was time when many Anti-Jewish interpolations appeared in texts of the New Testament (as a result, the Gospel of John is Anti-Jewish entirely, but the word Sabbath is excluded from Mark 13:18!). Finally we have no original Gospels today. It was Constantin who stopped persecutions, however what was the cost? He cursed the Jews legitimizing all previously accumulated Anti-Semitism and thus negated all the genuine Jewish apostolic tradition . 

The ostracism of the Jews was also a sequel of an ancient institutionalism, i.e. of a view that only conversion or rejection of faith by national leaders means actual conversion into this faith, or its actual rejection by the whole nation. Had 99 % of the Jews accepted Y-shua‘ as Messiah of Israel, but the king and the high priests not, then the whole nation should have been cursed, as deiciders. The main reason was that such a view was very profitable for a new priestly elite in Roman Empire. No one Gentile bishop in Palestine wanted restoration of the Jewish Apostolic Church.
Bloody conflicts between colonists Greeks and Jews in Palestine continued even up to the coming of Islam in the 7th c. As for Constantin, he had only stiffened imperial laws against the Jews.
On the other hand, Jews Christians, from their side, were not enough Jewish-patriotic – they could not participate in Bar Kokhba's revolt: Bar Kokhba had been proclaimed Messiah, but he was not that of the Messianic Jews who had already accepted JHS as Messiah. The insurgents did not want Messianics as well. 
The revolt suppressed in 135, the Messianic Jews concentrated in Pella in Galilea, where they could not defend themselves in a devasteted fatherland, increasingly colonized by the Greeks. In mass they escaped in more secure Syria and Arabia, later entering Aramaic Syrian Church and various Christian groups in Asia Minor and Arabia. No one Jewish bishof remained in fatherland, it looked like all of them had “disappeared”. 
The newly established Gentile Church started with cursing all the Jews as deiciders indiscriminately, except for a few dozen persons. Jews had to become Gentiles, not Gentiles had to enter the Covenant in the First Church, otherwise they were cursed! Why then should one be surprised that multitudes of former Christians have turned “the Jewish G-d” away today: He is not our G-d, we have own gods! This is only a final logical sequence of Eusebius' Anti-Jewish position: a dozen persons, reserved by Eusebius for his new Church, are no more necessary for Gentiles today. 
Thus a possible terrible crime of several leading persons before the Council of 325 in Nicea can be suspected. Nothing could alienate the Jews from Christ to such a degree for many following centures as these persons possibly succeeded to do. No one Jewish “Ebionite” was invited to the Council, since anyone had been already proclaimed a “heretic” in advance.
Consequently, after the Council of Nicea had declared all the Jews having betrayed JHS, it denied the Jewish calendar calculation of Pesach on Nisan 14. One of the nearest following regional Church councils (that of Laodicea, 364) prohibited the celebration of G-d-ordained (Ex=Đemôt 16:22, 23:12) Shabbat (but cf. Mt=Mattâj 24:20 !), as well as other Torah holidays. 
Therefore it is questionable whether one can name the Gentile Church (including its mutually cursed Roman–Constantinople counterparts of 1054, as well as further splitting Protestant branches – all a result of
Gen 12:3 ! ) apostolic only because of the uninterrupted lineage of laying-on of hands from the apostles, whose Church was betrayed by this new Gentile Church after hundreds of uninterrupted layings! (As for the same Anti-Jewish origins of the Protestants, remember Martin Luther, who was the first to convert Roman imperial - churchy Anti-Judaism into German racial Anti-Semitism and proposed to persecute Jews unmercifully, to subject them to forced labor and to set on fire their synagogues).
Of course, true believers in traditional Gentile churches always were and are redeemed by Christ in accordance with their faithfulness and love to Him, and this has served to fulfil the number of the Gentiles in the Kingdom of G-d  in centuries.