"...Paul, a probable convert to Judaism ignorant of the Torah, who even preaches the Torah's abolishment and does not preach the teachings of Jesus..." pg. 125 of Kosher Jesus by Shmuley Boteach
If that's true, then Paul, a man who claimed to be a "Hebrew of Hebrews" (Philippians 3:5), would have to be a liar.
So is there any basis for Boteach's assertion?
Boteach relies heavily on Hyam Maccoby in his research:
"My opinions on Jesus have been profoundly shaped by the writings of Hyam Maccoby..."(xi of Introduction)
"At face value, Paul's account is troublesome. First, it's unlikely Paul was a Pharisee or that he studied with Gamliel, the most advanced Pharisaic teacher of the time....Yet, as Hyam Maccoby points out, Paul is not only not a great scholar, he seems incapable of even reading Hebrew. When Paul quotes from the Hebrew Bible in his epistles, he uses the Greek Septuagint translation rather than the Hebrew. There are many situations in which the Hebrew Bible and the Septuagint translation differ considerably. Whenever they do, Paul follows the faulty Greek translation rather than the original Hebrew. No disciple of Gamliel would have thought to read the Bible in translation; there would have been no need," pg. 112
Yet actual scholars have called Maccoby's conclusions "wildly fanciful":
"Paul shows that he is as firmly located within Judaism as anyone can be; he is no first- or even tenth-generation proselyte. Maccoby's counter suggestion (Mythmaker, 95-96), that Paul was a Gentile...is a wildly fanciful and shows no sensitivity to Paul's whole argument in Romans," (James D. G. Dunn, Romans 9-16, World Biblical Commentary).
"Paul's mistakes make parts of the Christian doctrine he devised problematic. For example, one of Paul's most monumental claims is that Jewish law is no longer applicable after Jesus....To prove his case, Paul quotes from a law in Deuteronomy...However, Paul misrepresents the verse utterly. He says, 'Christ redeemed us from the curse of the law by becoming a curse for us, for it is written: 'Cursed is everyone who is hung on a pole.' Paul misquotes the Bible and gives it a fraudulent meaning. He explains that the pole refers to the Torah, the Law of Moses. If you hang on this pole--that is, if you are dependent on the law for salvation rather than the blood of Christ--you are cursed," pg. 112, Kosher Jesus.