Maybe he drank some dodgy cider again.
He doesn’t seem to fair too well when he comes up against Sam.
I think the problem he has with Sam is that Sam is able to bring Islam into the fold. For a large part it runs contra to Petersons interpretation of religious benevolence (to a point).
If Peterson focused his attention toward the thought, meaning and allegorical elements of religion (in many ways that he does in his book) he would fare better. The two are concatenate thinkers, Peterson able to more broadly back himself up with scientific elements and Harris in understanding of other religious doctrine.
One line that got me in the book where I think Peterson was right about religion was "It was in the aftermath of Gods death that the great collective horrors of communism and fascism sprang forth".
In many respects, humanity is more than a match for destroying itself when compared to what destruction God might level. God as an entropic or enduring being (not Being lol), is one of JPs weaknesses going against Sam.
If I were debating him I would be steering the conversation toward what people are capable of rather than divine messages. As an example, in this discussion he struggled to solidify the message around the verse in context of the paragraph, the paragraph in the chapter and the chapter in the book. By that token he could say mankind is able to do that just fine without religion: Examples being given (communism and the Gulag).
Having said that I've seen other people who share Harris's view manage to beat him at other arguments (or at least that was my perception)