In these verses the apostle opens the design of the whole epistle, in which he brings forward a charge of sinfulness against all flesh; declares the only method of deliverance from condemnation, by faith in the mercy of God, through Jesus Christ; and then builds upon it purity of heart, grateful obedience, and earnest desires to improve in all those Christian graces and tempers, which nothing but a lively faith in Christ can bring forth.
God is a just and holy God, and we are guilty sinners. It is necessary that we have a righteousness to appear in before him: there is such a righteousness brought in by the Messiah, and made known in the gospel; a gracious method of acceptance, notwithstanding the guilt of our sins.
It is the righteousness of Christ, who is God, coming from a satisfaction of infinite value. Faith is all in all, both in the beginning and progress of Christian life. It is not from faith to works, as if faith put us into a justified state, and then works kept us in it; but it is all along from faith to faith; it is faith pressing forward, and gaining the victory over unbelief.