Why does Les tell people who doubt his view to read Galatians 1 and 2?
They are told to read Galatians 1 and 2 because a careful, slow, open-minded reading can resolve doubts about the difference between Peter and Paul. They should not rely on a commentary or the speaker's words. If that reading does not open their mind, nothing else can.
Les explains that between verse 25 and 26 there is a gap he calls the three years, and to pick up the account one must go back to the book of Galatians. When people have doubts or wonder about his approach to the difference between Peter and Paul, he usually just asks them to read Galatians 1 and 2 carefully, slowly, and with an open mind. He tells them not to read a commentary or listen to what he says, but to read Galatians 1 and 2 directly. If that does not open their mind, he does not see how anything else can.
More Questions
Why does the teacher turn to Romans to explain Galatians?
The book of Galatians relates to Romans the way a pencil sketch relates to the finished oil painting: Galatians is introductory, while Romans makes the same truths a lot plainer.