How Minister to People Following Acts of Evil, 8

Taken from John Piper, 21 Ways to Comfort Those Who Are Suffering

8. Acknowledge that God has permitted a great outbreak of sin against his revealed will, and that we do not know all the reasons why he would permit such a thing now, when it was in his power to stop it.

Deuteronomy 29:29. "The secret things belong to the LORD our God, but the things revealed belong to us and to our sons forever, that we may observe all the words of this law." 

Romans 11:33-37 "Oh, the depth of the riches both of the wisdom and knowledge of God! How unsearchable are His judgments and unfathomable His ways! For WHO HAS KNOWN THE MIND OF THE LORD, OR WHO BECAME HIS COUNSELOR? Or WHO HAS FIRST GIVEN TO HIM THAT IT MIGHT BE PAID BACK TO HIM? For from Him and through Him and to Him are all things. To Him be the glory forever. Amen."