Packer and Beeke: Faith is not the ground of justification, but rather the instrument of receiving and resting in the person and work of Christ alone

“When Paul paraphrases this verse [Gen. 15:6] as teaching that Abraham’s faith was reckoned for righteousness (Rom. 4:5, 9, 22), all he intends us to understand is that faith—decisive, whole-hearted reliance on God’s gracious promise (vss. 18ff)—was the occasion and means of righteousness being imputed to him. There is no suggestion here that faith is the ground of justification.”
-J.I. Packer (quoted by Dr. Joel R. Beeke in “Justification by Faith Alone,” pp. 56-57)

“… Habakkuk 2:4 … quoted in Romans 1:17, Galatians 3:11, and Hebrews 10:38, is ultimately fulfilled in the righteousness that comes by faith in the gospel of Christ, for which the law itself teaches us to look (Romans 3:21-22; 10:4). Paul’s explanation of Habakkuk has inspired not only Martin Luther but countless other believers to place their faith in a righteousness not their own, but that of Jesus Christ who is called ‘THE LORD OUR RIGHTEOUSNESS’ (Jeremiah 23:6).”
-Dr. Joel R. Beeke, “The Relation of Faith to Justification” (in the book, “Justification by Faith Alone,” pp. 57-58)