I agree that "I believe X because it makes me feel Y" isn't a good argument. But it's also not a good argument to say "you believe X because it makes you feel Y." We could apply that, fallaciously, in any direction.

For example, I could say "you believe in pantheism because you find it comforting," or "you believe in materialism because it makes you feel like a strong, tough-minded person who does need that fuzzy comforting stuff."