The answer is in the next verse: God can know it.
This is kind of a problem for us. We live with ourselves so we are accustomed to our sins, so much so that we call most of our sins our “personality.”
People have a phenomenal ability to justify their sins and think they are good. But the wickedness of our heart defies knowing. It’s worse than you can imagine. Here’s one glimpse into it.
“Because they [the wicked] regard not the works of the LORD, nor the operation of his hands, he shall destroy them, and not build them up.”
Everything that happens in your life is a work of God, an operation of his hands. When we do not acknowledge this, say thank you, or even cast a glance His direction, we sin.
We are oblivious to God’s working. Instead we assume that we control all things. We sound too charismatic or superstitious or too something or other to see God at work in all things.
So we ignore Him, chalk up our victories to our own effort and our losses to our spouse’s efforts and carry on.
This is a single facet of the incurable, desperate wickedness of our hearts.