How do you call someone who is religious only because it makes them feel happy?

[Der/die AtheistIn]

This very much sounds like 'belief in belief' the idea that we must believe 'something', what that something is; they never define. Most cultural Christians belong in this category in that if they were subjected to close interrogation they would admit to no firm convictions regarding what they do actually believe, they don't know what they're supposed to believe. If they attend a church at all it is to meet family and friends and or, show of the new babby or the BMW, or catch up on the latest gossip. They know as much about the story of Christianity as a pig knows about going on holiday.

Mostly harmless.

My family fits this description pretty well. I was taught religion in school the fundamentalist way, and I believed that nonbelievers and pagans will go to Hell among other things. When my parents found out, they didn't talk enough to me. They talked, but not enough. Moderates are mostly harmless, but some of them, not necesarilly out of religion's fault, can do really stupid things.