The priest is to make atonement for the whole Israelite community, and they will be forgiven, for it was not intentional and they have presented to the Lord for their wrong a food offering and a sin offering. Numbers 15:25.
Because of our ignorance we are not fully aware of our sins of ignorance. Yet we may be sure they are many, in the form both of commission and omission. We may be doing in all sincerity, as a service to God, that which He has never commanded and can never accept.
The Lord knows these sins of ignorance every one. This may well alarm us, since in justice He will require these trespasses at our hand; but on the other hand, faith spies comfort in this fact, for the Lord will see to it that stains unseen by us shall yet be washed away. He sees the sin that He may cease to see it by casting it behind His back.
Our great comfort is that Jesus, the true priest, has made atonement for all the congregation of the children of Israel. That atonement secures the pardon of unknown sins. His precious blood cleanses us from all sin. Whether our eyes have seen it and wept over it or not, God has seen it, Christ has atoned for it, the Spirit bears witness to the pardon of it, and so we have a threefold peace.
O my Father, I praise Thy divine knowledge, which not only perceives my iniquities but provides an atonement which delivers me from the guilt of them, even before I know that I am guilty.
Charles H Spurgeon