For the Son of Man is come to save that which was lost.
Joseph Smith Translation
For the Son of Man is come to save that which was lost,
and to call sinners to repentance;
but those little ones have no need of repentance,
and I will save them.
1. The King James version is missing some (more) critical context.
2. "Son of Man" is used by JESUS to refer to Himself, so there is something important about that title. Joseph, his stepfather, is not his literal father. Then how does this title fit? Obviously his literal mother Mary is part of mankind, but I think there is more to it than that.
3. Perhaps CHRIST's meaning in JST Matthew 18:3 "Except you be converted, and become as little children, you shall not enter into the Kingdom of Heaven," means more that just becoming teachable. Maybe it also refers to becoming part of the group that CHRIST will save.
4. CHRIST's job is not to punish, it is to save and redeem, and to restore. We do a great job of punishing each other for small sins. I am sure Satan will do his job in punishing the truly big sins when we pass through the veil.
5. The greatness of GOD the Father's mercy, and CHRIST's atonement is nowhere better displayed than this one verse. Anyone who died prematurely is saved. No exceptions! No need to christen a child as soon as they are born. And, a baptism at eight is probably more symbolic of a child just beginning to become accountable, than it is of any sinfulness accrued to that point.
Let us sing praises to GOD and His Son (God the Son) forevermore!