Well, not all atheists are against God or something like that, some atheists just don't feel God anywhere because they are not born again and they also believe that God is too good to be true, but then there are these mean atheists who call us and even witches delusional. And some atheists are probably just possessed too.
In the end, it comes down to being hostile to God.
Romans 8:7 (NLT)
For the sinful nature is always hostile to God. It never did obey God’s laws, and it never will.