Our good works do not justify us. They do not sanctify us. They do not save us, but they are the “fruit and evidence” of a true and lively faith. Christ saved us by his obedience, death and resurrection. The Spirit sanctifies by his grace. Our good works are the fruit of God’s gracious for us and in us.
The logic is this: God graciously works in us new life and faith. Through that faith, we apprehend Christ and all his benefits for our salvation. Through that faith, the Spirit works union and communion with Christ in which we are sanctified, and out of that faith, union and communion are produced the fruit of our new life and sanctification in Christ. Fruit is a metaphor. As the Belgic Confession has it, good trees produce good fruit. The fruit is evidence of the life in the tree. So, the Spirit produces new life, faith, union with Christ, justification and sanctification in the sinner. Our good works are the fruit of the Spirit’s work in us and evidence of the salvation that we have by grace alone, through faith alone. Read the full article by R. Scott Clark.