One thing is what Jesus warned people about in His day. Jesus called a little child into the midst of the disciples to teach the lesson to be humble like a little child if they were to be great in the Kingdom of Heaven. "But whoever shall offend [stumble] one of these little ones which believes in me, it were better for him that a millstone were hanged about his neck and that he were drowned in the depths of the sea."
This is a horrific point - a child who believes in Jesus may be stumbled by people. That could prevent the child from coming to surrender his or her life over to God. (Though in God's will, that child may later come to do that.) When we consider the appalling evils that are being perpetrated on little children these days, it is no wonder if some become bitter against God, especially if some of the evil-doers claim to be Christians. There are a hundred and one things people can do to stumble children.
However, God knows all things, and even the worst evils people have done to children can be overcome by His sovereign grace, to deliver them to saving faith, in time.