Most likely they feel the general calling and are scared of the feeling they have. Think about it, they know in their heart there is a God yet they know in their earthly mind they can't prove it. They gathered together for support and attempt to convince each other that they are right. There is no other logical reason for this phenomenon.
Interesting theory brother.
It never has made sense to me as to why these people fight christians at every turn. Why would christians give them any concern at all? Christians run food banks and help out in disasters and do no harm to society, only good. Only real complain I can get from them is that they don't want to have to hear about God. Well I don't want to hear about the lifestyle of the immoral left. I don't want immorality and revisionist history taught in our schools.
I will, however continue to pray for atheist and try my best to love them.