The concept of justification, which was introduced into the theological vernacular in the 16th century, is laid out by St. Paul most elaborately in Romans. Chapters 2 through 6, in particular, speak of “justification.”
It is difficult to appreciate what Paul says without reading the introduction to the situation in Romans 2. Consider verse 25, If an uncircumcised man keeps the precepts of the law, will he not be considered circumcised? In chapter 3, he backtracks so as not to offend the Jews among his congregation in Rome. He rhetorically asks, What advantage is there then in being a Jew? Or what is the value of circumcision? Much in every respect. In the first place, the [Jews] were entrusted with the utterances of God.
In chapters 3 through 6, Paul tries to redirect the debate over the value of circumcision among his Christian followers in Rome, some of whom are Jewish and some of whom are not. He does this by speaking of justification before God. Paul makes a persuasive argument that we are not justified before the Lord either because we obey the letter of the law of scripture in general or the law of circumcision in particular. Remember that the covenant between God and Abraham required of Abraham’s male offspring that they be circumcised (Genesis 17: 9-10).
Paul argues that faith in Jesus Christ is fairly elemental to human salvation. Consider Romans 3:24, They are justified freely by God’s grace through the redemption in Jesus Christ. One of the greatest dangers is to elevate this discourse into “Paul’s Gospel,” as the Letter to the Romans is sometimes called. It is important to keep in mind that Paul’s theology does not supplant the witness of Mark, Matthew, Luke and John, which have much more to say on salvation than the axiom, we are justified by faith “alone.”
I read a blog by an evangelical Christian who suggested that faith precedes good works, but does not eliminate the need to perform them. I think there is common ground in that observation, since Thomas Aquinas concedes that an act of faith, and an act of charity, both have as their origin the grace of God.