The life of all Christians is entirely the work of God. We are brought from spiritual death to life simply by God's grace - that is his free and unmerited gift.
But because of his great love for us, God, who is rich in mercy, made us alive with Christ even when we were dead in transgressions — it is by grace you have been saved. (Ephesians 2:4-5)
So we want to acknowledge that everything we do is ultimately no more than a good work which God, in his grace, has given us to do (Ephesians 2:10).