How can the genitive mean “in” (Gal 2:16)?

Someone asked, “I am curious why Gal 2:16; 3:22, and Rom 3:22, 26, are translated as ‘faith in Christ’ when the genitive case is used.” Good question.

Gal 2:16 reads, “yet we know that no one is justified by the works of the law but through faith (διὰ πίστεως) in Jesus Christ (Ἰησοῦ Χριστοῦ).” The other verses are quite similar in their use of πίστεως Ἰησοῦ Χριστοῦ.

Someone once told me that a simple way to look at the genitive is to see all genitives as either subjective or objective, if the head noun contains a verbal idea. Either the word in the genitive produces (“subjective”) or receives (“objective”) the verbal idea in the head noun. This may be a bit simplistic, but it has helped me a lot through the years.

If Ἰησοῦ Χριστοῦ is a subjective genitive, then it refers to the faith produced by Jesus, his own faith; and so the KJV reads, “Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ.” The only modern translation I checked that goes this direction is the NET: “yet we know that no one is justified by the works of the law but by the faithfulness of Jesus Christ.”

If it is an objective genitive, then it refers to the faith received by Jesus. Most translations believe it is the latter (including the NKJV), but how do you say that we are justified by faith when Jesus is the object of our faith? In English, you say “in Jesus.” That is the answer to the question.

Part of translation is realizing that your task is to say the same thing in one language that is said in another; the nice, neat divisions we often create in first year Greek don’t ways let us do this. The genitive does not always mean “of,” and the dative does not always mean “in.” What you have to do is look at the deeper grammatical data, see what is said in one language, and try to say the same thing in the other language.