If the Lord can see everything in the world of the dead, He can see in our hearts.” Proverbs 15:11 (CEV)
God examines the inner-workings of the hearts of men. He is able to observe every secret thought and the development of the mindset of men. It is not just the immediate thought or idea that He directs His attention to. He looks at all that contributed to the formation of the thought long before it is given expression. This text expresses His gaze into the dark mysteries of the world of the dead. He has full knowledge of every detail existing there. Even the underworld of demons and devils all of the mysteries of hell, God knows. If death itself cannot shroud the degree of knowledge fully known by Him, then it should be clear to all that He knows the hearts or the inner life or the secret life of men or human beings. “How then can we hide our thoughts from God?” (TEV)
The Psalmist requested divine introspection from God; “Examine me, O Lord, and prove me; Try my mind and my heart.” Psalm 26:2 He did not trust his own judgments, but requested that God would show him what He sees in regards to the inner-workings of his heart. We need God to show us what we are incapable of seeing within ourselves. Only then will the Holy Spirit be allowed to free us from the vice grip of sins that in the past appeared justifiable. Then we can be cleansed of secret sins.