It should be no surprise that evil people exist in the world. Although some like to say there is a bit of good in everybody I disagree. Hitler was known to throw great parties but does that cancel out all the evil he did? No, he was pure evil.
Recently we hear about the enemy using humans as shields, even babies. This is evil. But there are evils that we don't read about and are kept in the dark. God commands us to shun ALL evil. Even relatives.
Why would we allow our children access to evil people? Just because we are related? Not according to God. Evil is evil.
A mother who doesn't protect her child from the hands of an evil man (child molestation, abuse, etc.) for her own ill gotten gain is as evil as a devout islamist using a child as a human shield to protect himself.
Christ Jesus can change the most evil wicked heart into a pure God fearing heart, but until this happens we are to shun them and protect the innocent from the harm they choose to inflict. No more religious card of forgive and forget. Forgive and let go. Unless they repent.
1 kings 3:16-28