Just a quote from J.I. Packer’s Knowing God on God’s grace.
“It has been said that in the New Testament doctrine is grace, and ethics is gratitude; and something is wrong with any form of Christianity in which, experimentally and practically, this saying is not being verified. Those who suppose that the doctrine of God’s grace tends to encourage moral laxity … are simply showing that, in the most literal sense, they do not know what they are talking about. For love awakens love in return; and love, once awakened, desires to give pleasure; and the revealed will of God is that those who have received grace should henceforth give themselves to “good works” … and gratitude will move any man who has truly received grace to do as God requires… “