Excerpt from Spurgeons Puritan Catechism (with proofs)

32.Q. What is justification?

A. Justification is an act of God's free grace, wherein he pardons all our sins (Rom. 3:24; Eph. 1:7), and accepts us as righteous in his sight (2 Cor. 5:21) only for the righteousness of Christ imputed to us (Rom. 5:19), and received by faith alone (Gal. 2:16; Phil. 3:9).