The infallible Scriptures emphatically declare that works cannot justify us in the sight of God (Romans 4:2-8; Ephesians 2:8-9; Titus 3:5-7; 2 Timothy 1:9). So the text of James 2:24 cannot be teaching us that justification is merited in part on the basis of human efforts. The surrounding context of this verse, as well as the rest of Scripture, plays a key role here.
In context, James clearly occupies the word justify to mean vindication, or proven. He does not argue against justification by faith alone, but rather, a salvation that stands without any good works to accompany it. In other words, one's lifestyle must be consistent with his or her profession of faith. Faith will certainly be accompanied with good works because our hearts are regenerate. If our Christian testimony is not supported with evidence of good character, then unbelievers will have no reason to deem our witness for Christ trustworthy or reliable.
What James is saying is that we demonstrate the reality of our faith by good works. Are we going to merely talk the spiritual talk or actually going to walk the spiritual walk (James 2:14-17)? Are we only going to be hearers of the Word or doers of the Word (James 1:21-22; 26-27)? The question that James addresses is, "Can such faith save a man?" It is not enough to mentally accept the fact that God exists (James 2:19-20). Therefore, James distinguishes between two different kinds of faith. The demons acknowledge that whatever God says is the truth, but are not in fellowship with Him because they lack trust.
Works are the product or result of a genuinely saving faith. A converted heart by definition will result in a changed life of holiness. James 2:18 especially echoes this theme. The inspired writer James provides two biblical examples to illustrate his point on the relationship between faith and works (James 2:21-25). The faith of Abraham and Rehab was tested and shown to be true. An analogy is employed to make the point that faith and works are not to be separated from each other (James 2:26). Consequently, the Christian walk is not devoid of good works.
James is not hereby discussing themes such as the blood of Christ or how one gets right with God, as does Paul (Romans 3-5). James occupies the term "justify" in the sense of vindication (not being declared righteous in the sight of God), which is employed in the same manner elsewhere throughout Scripture (Matthew 11:19; Luke 7:29; 16:15; Romans 3:4). The Apostle Paul in Romans and Galatians deals with the universal scope of man's depravity and condemnation by the Law, whereas James addresses the narrower scope of hypocrisy within the church.