How am I supposed to ask forgiveness for things I cannot even remember doing? The idea that something is unaccounted for keeps nagging at me.

“Who can understand his errors? cleanse thou me from secret faults.”

The psalm spends its first half on the sheer scale of creation and the goodness of God's law, then turns abruptly to the writer's own blind spots. He asks a question he cannot answer: who can even keep track of their own errors? Rather than attempting an inventory, he asks to be cleansed of what he cannot see. It is a request rather than an audit, and that is deliberate.

“But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.”

John is writing against a group claiming a spirituality that put them beyond sin's reach altogether. His alternative is walking in the light, which means living without concealment rather than living without failure. The cleansing he describes is continuous and comprehensive. It is not applied item by item as you manage to recall them, which is a relief for anyone whose memory is not a complete record.