1 John 4:4
Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world.
1 John 5:4
For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
1 John 5:5
Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?
Christ in you, and faith in Him. This is what overcomes.
So if I were to ask the question, what is it that overcomes, faith, or works, it seems the answer is, Faith in Christ in me.
Much love!