Richard Beck:
Some of this debate swirls around how we render Paul's use of the phrase Pistis Christou. What we all agree on is that pistis means "faith" in Greek and that christou means "Christ." ... Martin Luther, and those who followed him, translated Pistis Christou as "faith in Christ." But a growing number of scholars (e.g., Richard Hays, N.T. Wright) have argued that the proper translation of Pistis Christou should be "faith of Christ."
It’s amazing how one little word can completely change the meaning of a phrase. It’s also amazing how one little phrase can completely shape an entire theology.
“Faith in Christ” implies that we have to do something to attain our salvation; we must have faith. “Faith of Christ” places the burden on Jesus. It is because of his faithfulness that we are saved. That’s a pretty significant difference.
Words matter, especially the little ones.