My faith is really slipping.?

it literally goes through my mind all day. i feel like i'm agnostic yet when i see someone on here or any other site or just sittin around and someone tries to tell me that there is no god and people who wrote the bible are lunatics, i can't stand it. it pisses me off (i hate athiests) and i stand up for well, whati believe in i guess. but when i look at the science of it all it really brings me down. i have been a christian all of my life and i dont know what to do anymore? i feel like i don't believe but deep down i know i do