Our secret sins!
Secret sins are in some respects more dangerous than open sins.
The more inward and secret the disease is — the more the man is in danger of losing his life. There are no fevers so dangerous — as those that prey upon the inward parts.
Just so, there are no sins so pernicious to the souls of men — as those that are most inward and secret. Secret sins often reign in the souls of men most powerfully, when they are least apparent!
"You have set our iniquities before you, our secret sins in the light of Your presence!" Psalm 90:8