"Moses" here is a metonym here that stands for the law itself. AT: "Moses accuses you in the Law, the very Law in which you have put your hopes" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# If you do not believe his writings, how are you going to believe my words?
This remark appears in the form of a question to provide emphasis. AT: "You do not believe his writings, so you will never believe my words!" (See: [[rc://en/ta/man/translate/figs-rquestion]])