CLAIM: Greek grammarians debate whether or not this passage should be rendered as “faith in Jesus Christ” or “the faithfulness of Jesus Christ.” The first rendering is the objective genitive (“faith in”), while the second rendering is the subjective genitive (“faithfulness of”). Which is it?
RESPONSE: While many commentators make a big deal about this, it doesn’t significantly affect our understanding of this passage. Both translations affirm that all people come to Christ based on grace, through faith, and apart from works. That being said, we favor the objective genitive (“faith in Jesus”), rather than the subjective genitive (“the faithfulness of Jesus”) for a number of reasons:
First, while we could translate this with the subjective genitive (cf. Rom. 3:3; 5:19), the linguistic argument for the subjective genitive is not overwhelming or compelling. The NET takes the subjective genitive translation (“through the faithfulness of Jesus”), but also notes that this is debatable.
Second, pistis in Paul “almost always means ‘faith.’” We would need very strong contextual clues to render this as “faithfulness” (as in Romans 3:3). Note that in Romans 4:12 and 4:16, the same expression is used but it refers to Abraham’s “faith,” rather than his “faithfulness.”
Third, in this section of Romans (3:21-4:25), pistis consistently refers to faith in God or Christ. In this section, Osborne notes that “faith speaks of belief in Christ (seventeen times!).” Later, verses 28 and 30 simply refer to “faith,” which presupposes “faith in Christ.”
Fourth, the repetition (“through faith… for all those who believe”) shows that “God’s righteousness is available only through faith in Christ—but it is available to anyone who has faith in Christ.” That is, the first statement refers to the instrument of salvation (“faith”) and the second statement refers to the people who receive salvation (“those who believe”).
 Moo, D. J. (1996). The Epistle to the Romans (p. 225). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.
 Osborne, G. R. (2004). Romans (p. 94). Downers Grove, IL: InterVarsity Press.
 Moo, D. J. (1996). The Epistle to the Romans (p. 226). Grand Rapids, MI: Wm. B. Eerdmans Publishing Co.