What is the relationship between justification and works? Are good works necessary for salvation? The answer to this question is, Yes. Good works are necessary for salvation. At the same time, it depends on how one relates justification to good works when answering this question. (p281)Fesko locates good works within redemptive history, especially the prophecies of Jeremiah (31:31-34) and Ezekiel (36:16-37) where God promises to forgive sins and put a Spirit renewed heart that loves God's law within God's people. Good works are therefore an eschatological phenomenon. We live in the already/not-yet of our redemption. God's work has begun but is not completed, so our good works are always going to be imperfect. This already/not-yet tension means that:
...the ground of the believer's forensic status cannot and does not shift from the work of Christ to the Spirit-led works of the believer. (p289)
The Spirit led works follow, therefore, the believer's justification and are the cause of his justification neither in the present nor the future. Rather, these works are the fruit of faith. In the passages from Jeremiah and Ezekiel, neither do we see God's people first offering their good works and obedience, which then causes God to show mercy to them, nor do we see the pattern of covenantal nomism, where God makes a covenant with Israel, and then on the basis of God's antecedent grace Israel maintains their place in the covenant. (p290)Fesko resolves the apparent contradiction between Paul and James by noting that the primary problem James is dealing with is antinomianism. He quotes Machen:
The faith that James is condemning is not the faith that Paul is commending. (p220 Machen's Notes on Galatians, ed. John H. Skilton, quoted on p292)Further, Fesko notes that Paul and James use the term "Justify" differently. This is evidenced by the OT passages to which James appeals and the way in which he interprets these passages. While Paul appeals to Genensis 15:6, James appeals to Genesis 22 in chapter 2:23. James sees Genesis 22 as an almost prophetic-type fulfilment of the righteousness Abraham ALREADY had in 15:6 (p293).
We can restate the differences in Paul and James in the following manner: Paul is interested in explaining how Abraham is justified, whereas James is interested in explaining how Abraham's faith is justified. Abraham is justified by faith alone, whereas Abraham's faith is justified by works. (p294)So to sum up, I return to the opening question: why are good works necessary for salvation? Why can't we sin so that grace may abound?
...to say that works are unnecessary for one's salvation is akin to saying that the eschatological age has not been inaugurated, the law has not been inscribed upon our hearts, and believers are not indwelt by the Holy Spirit. This, however is an impossibility, which is why James says: "For as the body apart from the spirit is dead, so also faith apart from works is dead." (James 2:26) (p295)