Question

[Crossless2.0]

I assumed all atheist was out to prove there is no God.

I suspect most atheists understand the proper use of 'prove', so you'll find that this isn't a widespread thing among atheists. Remember, 'atheist' -- like 'theist' -- pertains to belief or lack thereof, not knowledge. Proof doesn't really enter into it.

A lot of atheist sure do call theist idiots, morons, ludicrous, etc. over believing in something that they themsleves dont believe in.

Some people don't see any value or integrity in believing risible and unverifiable claims. Go figure. 

It's not like the world is overrun with people who came to their sense of the divine by way of Spinoza, to take one example. Scratch a theist, and nine times out of ten you'll find someone who believes utter horseshit based on some story they read in a 'special' book. Explain what that has to do with conscientious intellectual inquiry. Honesty. Integrity.

I'll wait.