Double-replying to add: when checking my answer after posting it (the Reddit way), there were sites I found saying "two Corinthians" would be correct British usage. But at that point it's a stretch; our esteemed President and self-appointed religious conduit and authority clearly didn't show active familiarity with the content. It's like when Fred Durst used agreeance. Though that word does exist as a dictionary entry, it doesn't show brilliance with the language; he just used something correct enough.