Is there an appreciable difference between the power of discernment and revelation? Sunday school teacher molests girl during church. How did no priesthood holder get the inspiration to stop it? How was a man with these tendencies called to this position? It seems that discernment and revelation are what separates us from any other Christian denomination. Help me sort it out?
I know you asked about Discernment vs. Revelation, but given your example I think what you are really asking is the age old question of ‘Why does God let bad things happen to good people?’ After all why wouldn’t God step in to protect a child from a molester? Therefore if the LDS Church does receive guidance in the form of Discernment and Revelation then why would there ever a molester put in a position to hurt a child? And more generally how could anything ever go wrong with God guiding everything from moment to moment?
The answer is that God respects our Agency. He wants us to choose an activity that pursues good, but he respects that we can choose very, very, poorly at times. Therefore we can very much choose to do bad things to each other. Then there is also the fact that this life is a test. We are here to see if we will do all things the Lord commands. When we have trials and trauma do we turn to the Lord for aid and help? When we prosper, do we remember the Lord as the source of our blessings? These are the kind questions that we are here to find out about ourselves.
So while God could stop every bad thing from happening, it would be counter productive to our growth and education. So we have to deal with the effects of our poor choices and the poor choices of others, so that we can develop faith, and learn to repent and forgive.