Forms of δικαιοσύνη or δικαιόω (dikaiosunē, dikaioō; the respective noun and verb forms) occur eight times in James’ letter. The area debated primarily is 2:21–25. It is not uncommon for Roman Catholic apologists, for example, to argue against Protestantism that the only area of the Bible in which “faith alone” appears is in v. 24: “You see that by works a man is justified by works and not by faith alone.” Yet, Paul states in Romans 3:20 that “by works of the law no flesh will be justified in His sight.” Theologically, we might define justification as a “declaration that the person has been restored to a state of righteousness through belief and trust in the work of Christ rather than on the basis of one’s own accomplishment.” In short, James and Paul, by using forms of δικαιοσύνη, are not referring to the same concept and thus should not be seen as conflicting with each other.
The reason we can say this comes down to the variant usages of δικαιόω and its derivatives. In the classical period, the term referred variously to civility, morality, correction of injustice, and to make judgment. Within the LXX, the passage that is perhaps most familiar to students of Scripture is Gen 15:6, which James quotes in 2:23. Most commonly, the LXX term corresponds with the Hebrew צדקה (tsdqh), which clearly doesn’t refer to the Pauline forensic declaration 100% of the time. Even within the New Testament, the forensic declaration concept is not referred to 100% of the time. BDAG lists four possible usages, the latter three of which are utilized in the New Testament:
- to take up a legal cause, show justice, do justice, take up a cause
- to render a favorable verdict, vindicate
- to cause someone to be released from personal or institutional claims that are no longer to be considered pertinent or valid, make free/pure
- to demonstrate to be morally right, prove to be right,
Whereas the context in which Paul declares that “justification” is by faith alone in Romans 3–4 is clearly forensic declaration, a different meaning is used in James 2:21–25, where δικαιάω and δικαιοσύνη are used in the sense of validating genuine faith.
That James is not in conflict with Paul can also be observed from the texts. Note how James cites Abraham being “justified by works” at the time he offers Isaac on the altar (v. 21) . James says that this fulfills the scripture: “Abraham believed God, and it was reckoned to him as righteousness.” (v. 23) What Paul refers to as a forensic declaration of justification in Gen 15:6 is what James says is fulfilled in Abraham’s works. Thus, the two senses of δικαιόω/δικαιοσύνη between James and Paul are different because they are referring to two separate — though related — events. The same fulfillment sense of justification can be applied rightly to the example of Rahab in Jas 2:25. Verse 21 refers to this as faith being “completed” or “fulfilled” (τελειόω / teleioō) by works. Jamieson, Fausset, and Brown refer to this as “not was vivified, but attained its fully consummated development, and is shown to be real.” Peter H. Davids summarizes the point of the James passage: “The point of James’s argument, then, has nothing to do with a forensic declaration of justification; the argument is simply that Abraham did have faith,” and — regarding the nature of this faith, Abraham “had deeds flowing from that faith. His faith was not just ‘saying,’ but ‘saying and doing.’”
 All translations are the my own unless otherwise noted.
 John MacArthur and Richard Mayhue, eds., Biblical Doctrine: A Systematic Summary of Bible Truth, Logos ed. (Wheaton: Crossway, 2017), 932.
 Moisés Silva, ed., “Δικαιοσύνη,” New International Dictionary of New Testament Theology and Exegesis (Grand Rapids: Zondervan, 2014), 723–724.
 Ibid., 725.
 BDAG, 249.
 Robert Jamieson, A. R. Fausset, and David Brown, Commentary Critical and Explanatory on the Whole Bible (Oak Harbor, WA: Logos Research Systems, Inc., 1997), 2:489.
 Peter H. Davids, The Epistle of James: A Commentary on the Greek Text, Logos ed., The New International Greek Testament Commentary (Grand Rapids, Mich: Eerdmans, 1982), 127.
Adapted from a seminary paper.