Well, the fact that there were Jews around that didn’t choose to accept Jesus as the Messiah of Israel is evident, even within the Apostle’s writings themselves. The point was that no one could refute what actually happened, with Jesus being raised from the dead, with Him being taken up in the view of over 500 others — and thus, all they had was their *refusal* to believe and not any evidence to refute what happened.
Now, the Jews who did believe on Jesus as the Messiah of Israel, they also recognized, at that time, that He fulfilled the prophecies of the coming Messiah, besides being confirmed in what He did (i.e., what Jesus did) and then how He was raised from the dead, in addition to Jesus raising others from the dead.
But, in Israel’s history, there have always been those who have refused to believe and/or refused to follow what God said. So, that refusal to believe, by itself, is nothing special or new. What is significant, is the total inability of the leaders and others (who refused to believe) to refute anything that the Christians did, at that time or refute what had happened to Jesus.
All they would have had to do, to “knock it out” (at that time) would have been to refute anything of all the things that the Apostles said — or even what they *did* (as in the healings they did themselves, after Jesus was gone).
Again, a total inability to be able to do so. That’s the confirmation that we have from that time.
And as for whether the Torah allows for Christianity. Well, the all the Jews who were steeped and raised, all their lives on the Torah, obviously said yes. Paul says yes, and it appears he was a strong one for the Torah, especially considering he was initially “going after” Christians and trying to kill them — until — Jesus, the Messiah of Israel, spoke to Paul directly and Paul then saw where he was wrong. Paul’s testimony, being who he was, as far as a Jew, is a powerful testimony to Christianity.
As far as a testimony to the entire nation..., I think that Jesus gave that testimony to the entire nation and that you would be hard pressed to find someone (i.e., a Jew at that time and in that place) who would not be aware. Jesus did give that testimony to the entire nation. And a large number of Jews (and then Gentiles) accepted the testimony of Jesus, especially after God raised Him from the dead, which confirmed His testimony.
And finally, the witness and the testimony is there. A person can accept it or reject it, but it’s not because it’s not valid or not accurate. All that’s contained in the Bible, in what we’ve been able to find out about, has been shown to be accurate and valid.
Of course, that’s what it’s all about — in that you can accept what God has provided, in Jesus as the Messiah of Israel — or not. If you choose not to accept it — it doesn’t invalidate the evidence and the proofs that are there — it merely shows which side of God’s salvation, that He has provided, you are on.
Jesus as the Messiah of Israel is the salvation provided by God for Israel and the whole world.
I can’t help you much more than that.
Your constant invoking of the "new testament," of J*sus, and Paul is merely the fallacious argument of "assuming the consequent"--ie, "proving" the point in dispute by assuming and invoking it. The Torah is G-d's Ultimate Revelation. Why is that so hard for you to wrap your head around? Who dares deviate from it (or from Noachide Law for non-Jews) because someone allegedly rose from the dead? The True G-d has never risen from the dead because the True G-d has never died--because the True G-d is not a human being!
Perhaps one day when you have nothing else to do you might, just as a lark, read the thirteenth chapter of Deuteronomy and see why Jews (and all people) are forbidden to follow new religions?
Finally, your assumption that the purpose of religion is "salvation" illustrates your deep-set assumptions. Salvationism is a man-centered, humanistic concept. The True G-d is our L-rd, Father, and Master, not our servant.