Numbers 15:28

And the priest shall make atonement for the soul that sinneth
ignorantly
By offering his sin offering for him:

when he sinneth by ignorance before the Lord;
to whom it is known to be such, before whom all things are naked, open, and well known:

to make an atonement for him, and it shall be forgiven him;
upon that atonement made by sacrifice; so the forgiveness of the sins of all the Lord's people proceeds upon an atonement made by the blood and sacrifice of Christ: full atonement of sin and free forgiveness are not contrary to each other.