One bedrock principle of the Protestant Reformation was justification by faith. We are not justified by meritorious works but by our faith in Jesus Christ. However, this principle depends upon a particular translation of the Greek text.
The Greek in Galatians 2:16-17 has no preposition between the words faith and Jesus Christ. To connect them, translators must insert an English preposition. But which one? Since the Greek text uses the genitive case, the preposition “of” seems the most logical choice. Most Greek genitives, in fact, are translated in just this way. Verse 16 would then say that we are justified through the “faith [or faithfulness] of Jesus Christ” rather than our “faith in Jesus Christ.”
Does this word choice from “in” to “of” matter? Yes. Saying that we are justified by the faithfulness of Jesus places the focus on what he did for us rather than on what we can do for ourselves to make ourselves whole. What matters is God’s sheer grace—a love we cannot earn and do not deserve—not the acceptance of a certain formula of belief about Jesus or the good deeds we can perform.
If we are saved by Christ’s faithfulness to God, even to his dying on the cross for us, then our response to this astounding grace is to embrace a cross-shaped faithfulness of our own. When we act in faithfulness to God’s promise, which is that God always brings new life out of death and healing to a broken creation, then we continue Jesus’ own work of healing and reconciliation.