Psychosis is loosely defined as a break from reality. This feat can be accomplished by deciding to believe that something which is otherwise provably false, is instead true. For example "Jesus is the only begotten son of god, born of a virgin and rose from the dead after 3 days" and "The universe and everything in it was created in 6 days". There I go dumping on the Church again, I don't mean to do that, the Church fills many important social functions that government and other institutions can't begin to approach. But it's just so darn easy and psychotic behavior is one defining aspect of true believers: they gave their souls to Jesus.
People don't usually to do things like that without ulterior motives, it just feels wrong. One way to get around that feeling is through social pressure: "Hipsterism is cool", "Join the Marines", "There is no other God but Allah and Mohamed is his prophet", Join the YMCA because Jesus loves you". Subliminal belief is usually established by assuming that A must be true if B is true, then not addressing the truth of B just because it helps both make sense. That's called delusion.
Here: read this too: Pot Addicts