A contention that has roiled the scholarly community of New Testament studies in recent years is the question of what the apostle Paul means in Galatians 2:16, (and elsewhere) when he says “yet we know that a person is not justified by works of the law but through faith in Jesus Christ.”
Greek is an inflected language so function is shown by the endings on words. In the case of Galatians 2:16 it is a genitive construction, pisteos christou. Should this be translated “faith in Christ” or [the] “faithfulness of Christ”? These two choices are the objective genitive, in the case that Christ is the object of faith—the “faith in Christ” view, and the subjective genitive, in the “faithfulness of Christ” view. The difference between this is a theological perspective. Indeed, I have interacted with some who, adopting the subjective genitive view, say that we are saved by the faithfulness of Christ, the reality of the giving of himself as the redeemer. What often accompanies this view is that personal faith in the Lord Jesus becomes either secondary or not a factor in human salvation. Unsurprisingly, one often finds this view in a universalist perspective. All the world will eventually be saved, because it is Christ’s faithfulness and not the exercise of our faith that is determinative.
The barrier to this is that “in” runs counter to the whole tenor of the New Testament, where faith in the Lord Jesus is definitive. Mark Seifrid expands on the difficulties of proposing that Paul speaks of the “faithfulness of Christ.”
“We must note at the outset that the usage and understanding of ‘faith’ in earliest Christianity stands at some distance from this proposal. As we have seen, the New Testament authors without exception speak of believing in Jesus Christ as the means by which God grants salvation. Only five texts in the New Testament speak of the ‘faithfulness of Christ’ using the adjective pistos, [faith] a paucity which stands in stark contrast to the approximately 400 (both implicit and direct) references to faith in Christ in the New Testament.” Christ, Our Righteousness: Paul’s Theology of Justification. NSBT. (Downers Grove: Apollos, 2000), 140.
In other words, the vast majority of texts emphasize that believing in Christ as the object of faith is the meaning when we encounter faith and Christ.
Other exegetically significant texts include Romans 3:22, where Paul speaks of “the righteousness of God through faith in Jesus Christ for all who believe.” Those who argue for a subjective genitive would translate this as “through the faithfulness of Jesus Christ.”
In both Romans and Galatians, however, the context argues against this. That is, after Paul has described the faith in Christ/faithfulness of Christ he goes on in Galatians 2:16 to say “so we also have believed in Christ Jesus, in order to be justified by faith in Christ and not by works of the law.” The element of Christ as the object of the believer’s faith is certainly present. Similarly, in Romans 3, if we ask who Paul refers to when he speaks of this redemption in Christ? That is, who is it for? “For all who believe.” As Seifrid notes, to downplay or minimize the necessity of faith in Christ as the object of our trust is to mischaracterize the New Testament data.
While this question may have caused a good bit of consternation among scholars, it is certainly no ivory tower question! What could have more importance for anyone hearing the Gospel than to understand what the substance of its message is? Seeing these passages as calling for faith in Christ does not, however, diminish or negate the truth that the Lord Jesus did indeed carry out the work his father gave him to do, that he was faithful to him who appointed him. He did not shrink back from the suffering or the cross, but humbled himself, according to his father’s will. Upon that faithfulness, our salvation rests. We trust in the Lord because he always did those things that pleased God the Father, including going to the cross. Because he was faithful unto death, this is the foundation of the Gospel call, “Believe in the Lord Jesus Christ, and you will be saved.”