Religion & Atheism

Hey there, I want to discuss religion.

I don't really identify with any religion and I don't identify with atheism either. Both deal in absolutes that have yet to be proven. For religion, Christianity specifically, things get really murky in the realm of faith; a Google definition of which yields:

A strong belief in God or in the doctrines of a religion, based on spiritual apprehension rather than proof.

Atheism likewise cannot disprove the existence of God, its most similar analogue to faith being observations; scientific, philosophical or otherwise.

As I've said before, I don't identify with either. An identity that closely corroborates my ideology, though not fully, would be agnostic theism. My similarity with this ideology is that I cannot say whether a God(s) truly exists or not, however since I was raised Christian I often find myself praying in situations like exams and plane take off(s?) and landing; habits I doubt I will ever quit and I can't say I want to either. It provides brief respite in those situations that is very welcome.

What I want to discuss is this: Why are some religious and atheistic people able to so vehemently defend something they just feel? Atheists who may counter that science is not feeling, definitely, but how can you defend something you can't prove? To quote Gin rummy from the Boondocks, "The absence of evidence is not the evidence of absence". Religious people can hide behind faith as you can't effectively argue with someone who is adamant they "just know" they're right. For the atheists though, why can you so boldly state your claim?

My opinion is both camps are equally fallible, none is more correct than the other. I want opinions as to why atheists "know they're right".

While religious opinions are welcome, they don't hold my much of my interest. I'm from a very conservative and religious family and I think I've heard most of the reasons why religion is right. I'm more interested in the other side of the coin at this point.