To doubt something so basic as the Apostolic bonafides of Paul, which is testified by Paul himself, his way of life, the power of his writings, and the other Apostles, makes me doubt your entire salvation. It is very important that you repent of such heresy, lest something worse come upon you, since you are, basically, causing damage to portions of the word of God for those who hear you and do not know any better, not to mention all the damage you are doing to yourself by doubting the authenticity of large portions of the scripture.
Well, Rabbi, that’s not your job, is it? We live in a country with a First Amendment in the Bill of Rights and my beliefs (or lack of them) are my business, not yours. Right?