In a christian standpoint the term Sin is separation from God. If a man does not believe in God, he uncoupled from also connected to it ethical apparatus. Certain norms and rules do not apply to him so automatically, such as the Ten Commandments. Thou shalt not kill, it says what a devout Christian would therefore automatically be signed as correct, because he knows that the man was conceived in the image of God. In each fellow a certain extent met a thought of God. What you did for one of these my brethren, you did it to me, Jesus is played. That is, in addition to the separation of God means sin and the separation of certain ethical and moral rules. But this does not have to automatically mean that atheistic oriented people could not be committed to high ethical and moral ideals. but it thinks that it can initially be a departure from the Christian ethic. Because the faith ethics with it and, ultimately, a certain image of humanity and social system depends. Hinduism, for example, implemented the caste system, under which each person is born with his birth in a social caste from which he can not break out. In this respect, faith shapes the social system. Christian standpoint, however, there is the equality of all people, as already explained above. Therefore, it is not no matter what you think. Political ideologies can easily take on a kind of faith, then indeed has no God, but is itself a kind of religion. If you look at what, for example, Lenin and Stalin have created for crimes against humanity, or Hitler, it is clear that it does make a difference what you believe. And in this respect the Christian faith is a pretty good bulwark against many negative ideologies which treat people unequally. Those who believe in the Christian God, to deal properly with the people consequently. Course in Christianity black sheep, but in principle it is so. Love your neighbor as yourself. And most of all, love your enemies. Thus, Jesus radicalized the charity then if you have to love your enemy, you have to stop and think how that might look for. One can not just him fight more.