"... would not God discover this? For he knows the secrets of the heart" (Psalm 144:21).
There are many implications to the truth of this verse. First, there is nothing hidden from God. No secret sins really, He knows it all.
Second, since he knows our hearts, we ought to deal with him in the level of our hearts. That is, we ought to see to rightly relate to him. This requires a deep honesty and transparency before him. Too often we play our little games, as if we could hide who we really are. Yet, like our first parents, we are absurdly covering ourselves. it is ineffectual, impossible, and ridiculous to attempt hiding our hearts from God.
Third, this is a reason the Lord hates hypocrisy. He knows when our outward actions are a mere show. Clearly acting on sin is worse than just thinking about it, but both are damnable apart from Christ. We do not want to be whitewashed tombs.
Fourth, God knows the pain in our hearts. If anyone understands and can comfort us, it is the Lord, He sees and knows even better than we do ourselves. He is the One we can share with, talk to, meditate on, count on, and seek soul health from without any pretense.
So let us live, pray, confess, worship, and share from the heart. O Lord God, our hearts are open.