The comic isn't saying this is the main point of religions, it's only saying it's one thing that happens within religions. For example, religious communities have their own social norms that are fundamental to the religion, and allow for coordinated actions you don't see elsewhere, like an Amish barn raising.

I take a Jungian view that a major useful thing religions offer is a framework for relating to the unconscious. One key part of that is to have a clear sense of ethics, and to align ones actions with it, which is generally good for your mental health.