Taking this ridiculous non-issue semi-seriously for the moment:
I think there's something odd with me.
Yes.
Whenever I walk into a Christian bookstore, I get dizzy, disoriented, and sometimes a headache.
I don't buy it, but don't go into any Christian bookstores then. Problem solved.
I also feel awkward in churches of any number of Christian sects.
Don't go into any churches then. Problem solved.
I can also sometimes sense if a person truly believes in God
Does your Savior-Sense start tingling when they talk about Jesus or when you notice that they're visiting these churches and Christian bookstores you frequently go to despite them allegedly making you feel ill or awkward?
Congratulations, you have the power of sight and hearing. You're just a step away from being one of the X-Men.
and friendships with such people are usually brief.
It's not much of a friendship if you've already poisoned the well by pre-judging them based on your precognitive GODAR, and then determining that a friendship is unlikely to last.
If they behave like a tool, then don't be friends with them. If your only criteria for not forming lasting friendships with these people is just the fact that they believe in a God, though, then you're likely going to be very lonely.
I'm worried, real worried.
No, you're really, really not.
You, and you alone. This is entirely about your attitude, and your alleged related health issues are incredibly easy to solve by not going to places that make you feel ill.