I like how you used DSM 4, but one problem with your argument is your application of the symptoms. You applied them in a socio aspect as opposed to psychological one. Everything you described in 1-4 is considered acceptable behavior and is the way many religious people feel.
Just because you think it is delusional that Bush believes he is talking to god doesn't mean it is. This isn't something he has developed from a chemical imbalance (the basis of adult onset schizophrenia) it is something that was taught to him by the church.
Something that is taught to you is not a delusion. Hitler youth were not delusional in believing that Hitler had a direct connection to god, they were mislead and fed lies, just like in the church. there is a big difference.