Too many Christians live in constant despondency because they cannot distinguish between the rock on which they stand and the faith by which they stand upon the rock. Faith is not our rock; Christ is our rock. We do not get faith by having faith in our faith or by looking to faith, but by looking to Christ. Looking to Christ is faith.
Nor is it perfect faith, great faith, fruitful faith, strong faith that justifies. If we start qualifying our faith, we destroy the gospel. Our faith may be weak, immature, timid, even indiscernible at times, but if it is real faith it is justifying faith (Matthew 6: 30). Our degree of faith affects sanctification and assurance, but not justification. Faith’s value in justification does not lie in any degree in itself but in its uniting us to Christ and His glorious achievement. As George Downame illustrates:
A small and weak hand, if it be able to reach up the meat to the mouth, as well performs its duty for the nourishment of the body as one of greater strength, because it is not the strength of the hand but the goodness of the meat which nourishes the body.
Far too often we are prone to look to the quality of our faith, the quality of our conviction of sin, the quality of our evangelical repentance, the quality of our love for the brethren for confirmation of our justification, forgetting that it is Christ alone who saves by gracious faith alone.
– Joel Beeke, “The Relation of Faith to Justification,” in Justification by Faith Alone, 93– 94.