From The Heidelberg Catechism:
2. How are you righteous before God?
Only by true faith in Jesus Christ;
that is, although my conscience accuses me,
- that I have grievously sinned against all the commandments of God,
- and have never kept any of them,
- and am still prone always to all evil;
yet God, without any merit of mine, of mere grace,
- grants and imputes to me the perfect satisfaction, righteousness, and holiness of Christ,
- as if I had never committed – nor had – any sin,
- and had myself accomplished all the obedience which Christ has fulfilled for me;
if only I accept such benefit with a believing heart.