By Elder Epiphanios Theodoropoulos
Sin is what prevents us from believing in God, not reason. For this reason, if you tell an atheist to live six months according to the ethics of the Gospel, and they do it, they will become a believer without knowing it.
"I don't believe in God" is usually said by vicious and immoral people. There has not been found nor will there be found a person who is moral, chaste, virtuous, etc. and is able to say with ease: "There is no God!"