How do Christians justify lack of God's intervention during events where neonates get killed?

I simply can't reason about it. When let's say 1 month old child gets killed and dies in horrible pain, there was nothing for him to learn from this "lesson". He also had no possibility to commit any sin to be punished with pain for his sins. This is plain not right. If there's an omnipotent, all knowing , good being, then that being should intervene. In the end most of us - sinful humans - would try to help as much as we can in such situation.