From an interview with the MGMT duo themselves, Ben Goldwasser stated that:

I think Andrew is way more into the mystical side of things, and I’m way more into rational science and math stuff. I don’t have a lot of tolerance for the mystical and superstition, whereas he really loves getting into that. Every now and again we’ll have an argument about it, but we still love each other.

Goldwasser also clarified his religious positions, identifying as what I suppose is a sort of shade of non-denominational agnostic theism:

I don’t identify with any religion at all but I’m really interested in all religions. I would never want to associate myself with just one of them.

But it’s really up to the guy himself to define his own beliefs. The point is, these dudes may be druggies or partiers, but they’re not some satanic demons from hell or anything like that. They’re just chill dudes.