Atheists don't need to find arguments against god. Religions do this on their own.
Just an example: Bible says god is almighty, knows everything and is kind.
Why are there natural disasters and war?
If god knows there are problems, could help but don't want- he's not kind.
If god knows, wan't to help but isn't able - hes not almighty
If good could help, want's to help but doesn't know there are any problems- he doesn't know everything
possible answer of an christian: "That's because of Satan. He does all the bad things."
Wait! Satan aka Lucifer is an fallen angel. God created the angels. So he makes a failure? Thanks for helping my(yours?) argumentation.
Last argument: "Everything happens just because god want it to happen like this!" o.O
This argument will be repeated until the atheist fell to sleep or loses interrest in this discussion.
Similar argumentation is possible on all religions I know. (Of course I don't know all
)