There is nothing that can be hidden from God; everything in all creation is exposed and lies open before His eyes. And it is to Him that we must all give an account of ourselves (Hebrews 4:13 Good News Bible).
The Lord will sometimes tell me the secrets a certain person is hiding. He does that for two reasons:
Sometimes the lie is so obvious to the entire group that they want to shout it out for the person, but I won’t let them because truth has to be a personal discovery. But it can be humorous! It’s like the child that has eaten from the chocolate syrup jar and the evidence is all over its face. When asked if he got into the chocolate, he so sweetly and innocently denies any wrong doing. “Oh, no. I haven’t eaten any chocolate.” Even when lifted up to look in the mirror he doesn’t understand how all that chocolate got on his face.
This denial is so characteristically human. What makes us think we can hide anything from God? He is the only one who sees everything, and He is the only one who forgives everything. Arrange to have some private time with the Lord and tell Him the deep, maybe dark, secrets of your heart. Only He has all the answers you need.