The Westminster Larger Catechism in modern English question number seventy:
Q. 70. What is justification?
A. Justification is an act of God’s free grace towards sinners. In justification, He pardons all their sins, accepting and accounting them righteous in His sight, not for anything done in them or by them, but only because of the perfect obedience and full satisfaction of Christ, which is imputed to them by God and received by faith alone.