Christianity is not a religion; it is the announcement of the end of religion. Religion consists of all the things (believing, behaving, worshiping, sacrificing) the human race has ever thought it had to do to get right with God. About those things, Christianity has only two comments to make. The first is that none of them ever had the least chance of doing the trick: the blood of bulls and goats can never take away sins (see the Epistle to the Hebrews) and no effort of ours to keep the law of God can ever succeed (see the Epistle to the Romans). The second is that everything religion tried (and failed) to do has been perfectly done, once and for all, by Jesus in his death and resurrection.
For Christians, therefore, the entire religion shop has been closed, boarded up, and forgotten. The church is not in the religion business. It never has been and it never will be, in spite of all the ecclesiastical turkeys through two thousand years who have acted as if religion was their stock in trade. The church, instead, is in the Gospel-proclaiming business. It is not here to bring the world the bad news that God will think kindly about us only after we have gone through certain creedal, liturgical, and ethical wickets; it is here to bring the world the Good News that “while we were yet sinners, Christ died for the ungodly.” It is here, in short, for no religious purpose at all, only to announce the Gospel of free grace.
The Parables of Grace, Eerdmans, 1988, 99-100.