Even an uncircumsized baby was "cut off from his people; he has broken My covenant," according to Genesis 17:12-14. An eight-day-old covenant breaker.

Moses was nearly put to death because he had neglected to circumcise his own son (Exodus 4:24-26). Not that circumcision saved Moses' son's soul, but it certainly saved his son's physical life (not to mention Moses' own life) because he would have been "cut off from his people" as a covenant breaker - child or not.

As I said in a previous post here, the mere fact that babies are mortal is proof that they are inherently guilty, since death is part of the curse upon Adam.

Why is this important? Because as others have said, the depravity of humankind is at the center of the debate about predestination.

Why, if mankind's nature has not been inherently corrupted, must God predestinate some to be conformed to the image of His Son (Romans 5:30) when all are made in God's image already? What happened to the image of God in men that it needs to be "conformed" to anything else?

The depravity of humankind is central to this larger question of predestination (we are still talking about predestination, right? Because there are multiple threads on this other topic).