I think a lot of atheist are former Christians or even Catholics who have become disillusioned with the faith and/or have read a lot of the anti-Christian rhetoric of the socialists or Marxist. At least this is how my son became one.
They think that religion was the cause of the poor remaining suppressed by the rich and powerful. They blame the spread of Christianity for the collapse of indigenous cultures. They condemn the colonial conquests and crusades started in the name of God. Some of what they say have a small grain of truth, but they forget that much of the evil done was by individuals or countries who used religion as an excuse to justify world conquest or greed.
The fact of the matter is, IF these countries or individual had properly followed their religion, most or all of these atrocities would never have happened. It is their perversion of their religion that these things took place. The evils of the world are not the result of having God in the world, but it is the result of having Godlessness in it. It is the absense of God within men’s heart that evil exist. To eliminate God from the world will not prevent evil, but make it flourish even more.
The Hitlers and Attilas of the world were NOT God-fearing folks. Some may have used God or faith to forward their own agendas, but that was a subversion of faith. Had these folks truly followed God in their hearts as they should they would have never crossed the line.
The biggest fault with atheists is that they no longer recognize God or faith as good. They see evil in the world and they see that sometimes it is perpetrated by folks who claim some sort of religion (or by some conflicts between religions) and they conclude that IF God really does exists, then He would never allow this to happen.
Or they think that IF God exists, then He surely would have proven Himself to them by now. Maybe they are waiting for some miraculous event or supernatural happening. But the sad thing is even IF such a thing would happen, they probably would not recognize it or accept it for what it is.
For people who believem we seem to see God’s handiwork in just about everything in our lives.
For folks who do not believe, God is completely absent from the universe. Everything is explainable either by science or by coincidence or by mass hysteria or delusion. Miraculous things or events are hoaxes or aberrations or parlor tricks. The question they can never answer is, what is it that would change or open their minds/hearts to believe ?
Even IF Jesus, Himself, came back today and performed the miracles that He did almost 2000 years ago, would they believe ? Sadly, they pobably would not.