One argument against Christianity begins with suffering: a good and all-powerful God would never allow the suffering of the innocent. There is an understanding of goodness and of power here that should be challenged, but first it must be said that suffering has meaning in an argument against belief in God only if suffering has meaning at all. Its presence means nothing if one takes a thoroughly materialistic point of view. It has meaning that can be used in a moral argument against belief only if we know or sense that it should not exist. But from the point of view of a serious and consistent nonbeliever, suffering is simply there: we hurt, suffer loss and pain, have pain inflicted on us by others or by nature, and it has no deep, or even shallow, moral or ontological significance. On this view any sense that suffering and death are wrong, that they are violations of something important to our being, is simply mistaken.
If suffering exists and is wrong, something about the universe, intrinsic or extrinsic, makes it wrong. Some sort of deep presence or divinity is responsible, one that is malign or culpably indifferent. The sense that even some atheists have that our suffering is a wrong done to us is interesting. It seems to stem from anger at God for not existing, or for not exercising power as they believe a good God should exercise power.