“…the righteousness of God… by [the] faith of Jesus Christ, unto all and upon all them that believe” (Rom. 3:22).
Note, the Apostle Paul here does not refer to faith in Christ, but the faith of Christ. Nor does he refer to what Christ believed, but rather to His worthiness to be believed, His fidelity, His trustworthiness.
We must not forget that faith is a reciprocal matter; it is two-sided. One side is objective; it believes in another. The other is subjective; it is a trustworthy character. One refers to what a person does; the other to what he is. If I have faith in you, you should keep faith with me; you should be trustworthy.
Seven times in St. Paul’s epistles he refers to “the faith of Christ” and each time his purpose is to emphasize our Lord’s worthiness of our complete confidence. That he does not refer to our faith in Christ is evident on the surface in each case. In the passage above he declares that the righteousness of God, which is “by the faith of Christ,” is conferred “upon all them that believe” (Here’s your faith in Him).
Similarly, in Gal. 3:22 he states that “the Scripture hath concluded all under sin, that the promise, by faith of Jesus Christ, might be given to “them that believe.” Here again, we believe because He is worthy of our confidence.
Again in Phil. 3:9, the Apostle expresses his desire for a righteousness not of his own, “but that which is through the faith of Christ” — and then adds: “the righteousness which is of God by faith.” Here’s man’s faith again! He has faith in Christ because Christ is completely faithful, completely worthy to be believed in. He paid the full penalty for our sins and is now in heaven dispensing the merits of Calvary — riches of grace, mercy and forgiveness.
But remember, “the faith of Christ” always precedes our faith in Christ. What good would it do us to believe in Him for salvation if He were not wholly to be relied upon for this? But He can be trusted “to save… to the uttermost [all] who come unto God by Him” (Heb. 7:25). source