Why fight about God???

If you believe in God, as I do,then live your life the way you believe you should. But our country is based on freedom. So why fight with those that believe different than you?? Why can't people just let people believe what they want and accept them for who and what they are? why do Christians feel like they have to force religion on people and why do atheists believe they have to spend their lives trying to prove God doesn't exist?

Why not just get along and let each person live as they want and believe as they want.

I just don't understand all the stupid fighting