Galatians 2:16
King James Version
16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
I believe the KJV got it correct and there's no problem with this. We are save by the 'faith of' if 'we believed in Jesus Christ".
The problem is when people try to argue that "OF" implies that it's Jesus' faith and NOT OUR faith, as if we don't exercise faith "IN" Christ.
Other verses in the KJV say faith "IN" Christ.
Acts 24:24 - And after certain days, when Felix came with his wife Drusilla, which was a Jewess, he sent for Paul, and heard him concerning the
faith "IN" Christ.
Galatians 3:26 - For ye are all the children of God by
faith "IN" Christ Jesus.
Ephesians 1:15 - Wherefore I also, after I heard of your
faith "IN" the Lord Jesus, and love unto all the saints,
Colossians 1:4 - Since we heard of your
faith "IN" Christ Jesus, and of the love which ye have to all the saints,
Colossians 2:5 - For though I be absent in the flesh, yet am I with you in the spirit, joying and beholding your order, and the stedfastness of your
faith "IN" Christ.