Properly understood, I think both translations are correct.

Fig.A, Luther's Bible

This post deals with translation of Luther and the KJV  on passages like Gal 2:16 from the Greek. This topic deals with "faith in Jesus" or "faith of Christ". Is one more "correct" than the other? Or, both are correct depending on understanding?

Before proceeding, please be reminded of the disclaimer I have in this blog, shown to the right of this page. I make another disclaimer that I am no NT Greek expert but I did have university training on it and thus can vet what scholars are saying, and that English is not my native language. Thus please consider - caveat emptor.

This is a result of my reflection and research on this passage, thus far.

Fig. B, Luther's Translation Gal 2:16

Believe me though, in this post, you do not need to have full Greek knowledge to understand what is going on in the mind of the translators.

Fig. C, KJV Gal 2:16

In Fig B, below I show how Luther's Bible translated Galatians 2:16. I highlighted the passage in question. Luther's German says "Glauben an Jesum Christum", in English "faith in Jesus Christ".

In Fig C, we show how the KJV translated this phrase w my highlighting, "faith of Christ". KJV is not the only one which translates this passage in such a way. The Roman Catholic Douay-Rheims translates it the same way, and a few other translations too.

In the Textus Receptus, this comes from the phrase δια πιστεως ιησου χριστου. 

Translating word for word, first without respect to conjugation we have δια is "through",  then πιστεως is "faith", then as we can discern  ιησου χριστου is "Jesus Christ". This πιστεως is in the so called genitive. Genitives are ordinarily gives the notion of possession. Should this be translated "faith of Christ"? Meaning the faith that belongs to Christ? Then why did Luther translated this to be "faith in Christ". Was he wrong? In fact, some blame Luther for influencing the many English translations we now have this way., ie the use of IN Christ. I saw one complaint on this.

I am not here to defend Luther, just the facts.

This boils down on how to treat this genitive - is it subjective, ie, the faith that belongs to Christ or is it objective, the object of this faith is Christ? The translator seeing this has to decide the best way to render its meaning.

Looking at the literal translation as much as we can, reflect for a minute the meaning of --- the faith that belongs to Christ ie faith of Christ, did not Jesus say this -- John 14:1 - you believe in God believe also IN me? In other words, where does your faith belong, is it not supposed to belong to Christ? Hence, if so, "faith IN Christ", ie Luther's translation give it out clearly too. That is not a bad translation as the context also bears this out - see "even we have believed in Jesus Christ" , thus faith IN Christ is OK rendition.

Let me now illustrate this rendition from a quote from Thomas Edison using similar language.

Fig D. Edison Quote

Please read the context of what Edison said about his mother. Note the 2nd to the last line - "My mother is the making of me". Did Edison make his mother? In effect, the subject is Edison, did he create his mother? No. In the context he meant his mother was the cause of him being in the right path, it was his mother who MADE him this way, thus it was his mother as the subject and "me" ( Edison) the object. His mother made him for what he is today. 

In conclusion, properly understanding the meaning of this genitive construction, both IN Christ and OF Christ are correct.