The Systematic theology of the "One Faith Two Expression" theology or "Two Torah" Theology is the theology of much of Messianic Judaism including the majority of the IAMCS and the UMJC.
In his book Jewish Roots Daniel Juster has a similar illustration for this same theology. Juster first illustrates the Dispensationalist view with three circles which do not overlap at all which he lables "Jews" "Church of former Jews & Gentiles" and "Gentiles" (p. 35). He then gives his own correction of this view with an illustration of three circles, with each of the two outside circles overlapping with the circle in the middle. The two outer circles are labled "Israel" and "Gentiles" while the middle circle is labled "The Church". This results in two groups in "The Church" which Juster calls "Jewish followers of Yeshua" (i.e. Messianic Judaism" and "Gentile followers of Yeshua" (i.e. Gentile Christianity).
This is the live and let live theology of much of Messianic Judaism. They maintain that Messianic Jews and Gentile Christians are united together as one big "Church" or "Body of Messiah" together, They maintain that These two groups are simply culturally different expressions of the one true faith. They maintain that it is culturally appropriate for Messianic Jews to observe Saturday as the weekly day of worship, keep biblical Jewish holidays and eat kosher. On the other hand Gentiles are free to incorporate the Sabbath principle into a weekly Sunday worship, celebrate Christmas, Easter and other pagan holidays, eat unkosher foods etc. because they need not leave their gentile culture to join the Jewish "culture" of Torah observance.
Yeshua ("Jesus of Nazareth") did not come to found a new religion, he came to be Messiah of the old one. Yeshua lived his entire life without ever violating Torah, yet creating a new religion itself would have been a Torah violation. The original followers of Yeshua were not part of a new religion, they were a sect of Judaism. Not one "New Testament" writer refers to himself as being a "Christian" yet Paul continually identifies himself as Jewish (Acts 21:39; 22:3) and on one occasion he even declares "I am a Pharisee" (Acts 23:6).
Now I know that within many Christian circles there is a teaching that says that originally Judaism was the true faith but that it has now been replaced by a new faith "Christianity" which is now the true faith. This theology is totally counter to the teachings of the "New Testament". The "New Testament" is plain in telling us that there is one true faith (Eph. 4:5) which was given once and for all time (Jude 1:3). This means that the theology that claims that Christianity is a true faith which has replaced Judaism which had been the previous true faith is absolutely false! There is, according to the "New Testament" itself ONE TRUE FAITH and it was ONLY GIVEN ONCE. Christianity is to young to be that ONE true faith that was ONCE given, that ONE true faith that was ONCE given therefore MUST be Judaism!
But these sectarians… did not call themselves Christians– but "Nazarenes," … However they are simply complete Jews. They use not only the New Testament but the Old Testament as well, as the Jews do… They have no different ideas, but confess everything exactly as the Law proclaims it and in the Jewish fashion– except for their belief in Messiah, if you please! For they acknowledge both the resurrection of the dead and the divine creation of all things, and declare that G-d is one, and that his son is Y'shua the Messiah. They are trained to a nicety in Hebrew. For among them the entire Law, the Prophets, and the… Writings… are read in Hebrew, as they surely are by the Jews. They are different from the Jews, and different from Christians, only in the following. They disagree with Jews because they have come to faith in Messiah; but since they are still fettered by the Law–circumcision, the Sabbath, and the rest– they are not in accord with Christians…. they are nothing but Jews…. They have the Goodnews according to Matthew in its entirety in Hebrew. For it is clear that they still preserve this, in the Hebrew alphabet, as it was originally written.
11 And many false prophets will arise, and will lead many astray. 12 And because apostasy will abound, the love of many will wax cold.
What does it mean "depart from the faith"? There is only one true faith (Eph. 4:5) which was once and for all delivered (Jude 1:3). But that faith was Judaism not Christianity.
I know that after I am gone fierce wolves will enter in among you without mercy upon the flock. And also from among you there will rise up men speaking perverse things, so that they might turn away the talmidim to follow after them.
Paul seems to indicate that after his death leaders would begin to rise up in his stead that would draw people to follow themselves and draw them away from Torah. Perhaps the some of the very men who had twisted Paul's teaching into anti-nomianism would one day become the leadership. In fact Paul died in 66 C.E. and the first overseer (Bishop) of Antioch to take office after his death was Ignatius in 98 C.E.. Ignatius fulfilled Paul's words precisely. Upon taking the office of Bishop over Antioch Ignatius sent out a series of epistles to other assemblies. His letters to the Ephesians, Magnesians, Trallianns, Romans, Philadelphians and Smyrnaeans as well as a personal letter to Polycarp overseer of Smyrnaea have survived to us.
…being subject to your bishop… …run together according to the will of God. Jesus… is sent by the will of the Father; As the bishops… are by the will of Jesus Christ.
…your bishop… I think you happy who are so joined to him, as the church is to Jesus Christ and Jesus Christ is to the Father… Let us take heed therefore, that we not set ourselves against the bishop, that we may be subject to God… . We ought to look upon the bishop, even as we would upon the Lord himself.
…Do nothing without the bishop.
By exalting the power of the office of bishop (overseer) and demanding the absolute authority of the bishop over the assembly, Ignatius was actually making a power grab by thus taking absolute authority over the assembly at Antioch and encouraging other Gentile overseers to follow suite. In the past such disputes were resolved by the Nazarene Sanhedrin of the Nazarene assembly in Jerusalem (Acts 15).
let us learn to live according to the rules of Christianity, for whosoever is called by any other name besides this, he is not of God… .
(This is the first time in History that Christianity is characterized as a new and different religion apart from Judaism).
Now Paul's prophecy was being fulfilled. Gentile leaders were causing men to follow after themselves and drawing people away from Torah, and it was springing forth from the first Gentile assembly. The result was the birth of a new Gentile religion that had effectively rebelled against Torah based Judaism, a religion known as Christianity.
Hegisippus indicates the apostasy began the very same year that Ignatious became bishop of Antioch!
According to the Torah, Jews and Gentiles must follow the ONE Torah.
THE GREAT COMMISION: GO TEACH THE GENTILES TORAH!
Yeshua told his original Jewish followers to go teach the Gentiles "to observe all that I have commanded you [Jews]." The Great Commission was a commission to the Jews to go teach Torah Observance to the Gentiles!
There is one Torah and one true faith. That true faith is NOT the "Church" nor is it unified with Gentile Christianity. Sunday keeping, celebration of Christmas and Easter and Torah rejection is *NOT* a Gentile cultural expression of the true faith, it is not an expression of the true faith at all. There is only one expression of the one true faith and that is observance of the one Torah of the one true faith.