For by grace you have been saved, through faith, and this is not your own doing; it is the gift of God, not a result of works, so that no one may boast.-Ephesians 2:8-9
Abraham believed God and it was counted to him as righteousness.-Romans 4:3
Sola Fide was one of the grand biblical ideas recovered during the Protestant Reformation. Following after Luther, reformation theologians helped to remind the church that salvation is accomplished by grace alone (sola gratia) through faith alone (sola fide) in the finished work of Christ alone (solus Christus). My salvation is based not on my good works, my character, nor which church I attend, but upon faith in the finished work of Christ.
Too often though, Christians have a way of taking that glorious gift of grace and repackaging it into works based salvation. We give assent to salvation by faith alone, but then begin to ask questions like, "but is my faith enough?" and "how much faith is required for it to be a saving faith?" Turning faith into works brings us right back to square one, where salvation depends on me. But how much faith is necessary?
In Matthew 17, Jesus is talking with his disciples and he tells them, "truly I say to you, if you have faith like a grain of mustard seed, you will say to this mountain, 'move from here to there' and it will move, and nothing will be impossible for you" (Matthew 17:20). This is not a verse about how a little belief makes me stronger in my own self. It is a verse that tells me that even a weak, anemic faith is sufficient. With my little faith, Christ saves.
So today, if you find yourself saying, "my faith is so weak. Jesus all I have to bring is a mountain of doubt and a molecule of faith", Christ can redeem that for "nothing will be impossible" with him.
My salvation is all of grace, all of faith, and all of God.