Now, if I think that Christianity is stupid (and I do), then it is not discrimination to call every single Christian a dumbass, because they believe in it. Discrimination is when you judge people by something they did not choose, like gender or race.
If you think that anyone who has some view you find stupid is a "dumbass", then you pretty much have to call everyone one who isn't you.
Unless you exclusively hang out with people whose worldviews and opinions are only the ones you personally find acceptable.
Seriously, you're being an internet philosophical tough guy here. There are a lot of reasons people become (or are, or stay) religious, and even if a religion doesn't hold up to scrutiny, someone who believes in it (which, again, could be for a multitude of reasons) can still otherwise be an extremely intelligent person.
Singling out one particular belief or quality about people and then making rash judgements about their entire character DOES make you bigoted.
And this is coming from an atheist who isn't too friendly with the concept of mainstream Western religion. One who's known a lot of Christians (some of whom still are and some of whom aren't), many of whom were/are good and intelligent people despite holding beliefs I feel are ill-reasoned.
Not to mention you can't whine about discrimination till your a minority.
... Huh? Of course you can.
Being bigoted against a group is wrong no matter what. I'm white, but if someone acts racist towards me, that doesn't mean I have to take it or that it shouldn't be discouraged.