Michal took the teraphim statue and placed it on the bed, and she put a net of goat hair at the place of [David’s] head, and she covered it with a garment.
~1 Samuel 19:13

Why did David’s wife, Michal, have a teraphim idol if God had forbidden their use (Exo. 20:4,5)?

The Watchtower gives a possible explanation in that her heart may not have been complete toward Jehovah and it is possible that certain superstitions still influenced Israeli culture.

Perhaps David did not know about the idol, but it is also possible that he let her keep it because she was the king’s daughter (Watchtower 06-01-04, p.29, “Questions from Readers”).
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With that the king said to the guards stationed around him: “Turn and kill the priests of Jehovah, because they have sided with David! They knew that he was a runaway, and they did not inform me!” But the king’s servants did not want to lift their hands to assault the priests of Jehovah.
~1 Samuel 22:17

The guards in this story are a fine example of fearing God instead of man (Matt. 10:28).

When human authorities come in direct conflict with God’s will, the right thing to do is to carry out God’s will (Acts 5:29).

This principle alone would avoid modern cases of genocide.