And history speaks against you on this -- in that they were considered fully Jews-- in Jerusalem, while accepting Christ as the Messiah. In fact, there were those of the ruling religious class in Jerusalem who accepted Christ as the Messiah.
So, even history speaks against you.
You will find that the Christians and Jews are coming together -- with our brethren of the Messianic Jews forming the bridge -- bringing things back to where it was with the First Christian Church in Jerusalem.
We are coming to that time when all will be joined -- with the Messiah returning.
I'll put it to you this way. The Messiah who returns and builds the Temple in Ezekiel, will be accepted by the Christians, fully and without reservation.
You will not find a single Jew from across the spectrum of liberal to haredi Jews who would accept a Messianic Jew as truly being Jewish.
The JEWS who do accept Jesus as the Messiah would disagree with you -- AS JEWS. They will maintain by all other standards -- that they are Jews (and rightfully so), while they do accept Jesus as Messiah. They are a witness against other Jews.