Assalamu alaikum Brother Yusuf, I am presently reading his book 'Lost Christianities' and I am amazed at the level of his research and scholarship.Professor Bart D Ehrman being one of my chief sources,
The book of Galatians was very revealing to me about Paul's claim to be a Messenger of God as in 1:11-12 I want you to know, brothers and sisters, that the gospel I preached is not of human origin. I did not receive it from any man, nor was I taught it; rather, I received it by revelation from Jesus Christ. This is a claim not to be taken lightly and accepted out of hand as it is the basis for all that Paul wrote. This very point was apparently a point that the unbelievers of Mecca challenged Prophet Muhammad (sal alahu alayhi wa salam) on because the Quran itself defends him and addresses it with statements establishing his Messengership such as Quran 68:2-6 You (O Muhammad), by the Grace of your Lord, are not mad. And verily, for you will be an endless reward. And verily, you are on an exalted (standard of) character. You will see, and they will see, which of you is afflicted with madness.we can now learn that:
1) Paul claims to be a Prophet and teaches a NEW Gospel NT taught by Jesus, PBUH, in his "Earthly" ministry [see other of my posts]
2) EVEN Paul's corrupted teachings are further corrupted "35 to 85 years after Paul's death" to quote the site.
Christians gloss over the fact that Paul never even met Jesus while he was on earth and yet he claims to know the 'Gospel' better than those disciples who did follow and listen to his Message while he walked among them. Your last point is also interesting in that not only did Paul not follow Jesus, other people took liberty with writing their own epistles or letters in Paul's name as one of authority. The key question for Christians is, "Where is proof for God's 'inspiration' in any of the writings of the Bible?"