This does indeed sound rash and harsh to our minds. However, we do well to remember that our minds are but sinful and that our feelings and emotions can stand in the way of a correct perspective on this. God hates sin. They are all totally sinful. This is true for people of all ages, for infants as well as the elderly.
Scripture says that all men sinned - and the wages of sin is death, eternal, spiritual death.
My sinful emotions may not hinder me from humbling acknowledging the sentence God rightfully may pronounce on every human being, regardless of age. Only when it is clear in my mind what I and all people by nature deserve, can I be amazed that God has actually reached out to save some . The result of the fall into sin was total depravity. The effect of the fall into sin is that the heart is changed, depraved, corrupted. This doesn't mean that all people all commit all the most radical, horrendous sins possible.