"Where does the identity of Christian faith lie? Its outward mark is church membership. This, however, takes us no further, but merely moves the problem on. For the Christian identity of the church is itself questionable, when the form it takes is affected by so many other interests. One can point to the creed. To repeat the formula of the Apostles’ Creed is no guarantee of Christian identity, but simply a loyalty to the fathers and to tradition. One can point to particular experiences of vocation, conversion and grace in one’s own life. But even they do no guarantee one’s identity as a Christian; at best the point to what one has begun to believe in such experiences. Ultimately, one’s belief is not in one’s own faith; within one’s experiences in faith and in one’s decisions, one believes in someone else who is more than one’s own faith. Christian identity can be understood only in an act of identification with the crucified Christ, to the extent to which one has accepted the proclamation that in him God had identified himself with the godless, and those abandoned by God, to whom one belongs oneself. If Christian identity comes into being by this double process of identification, then it is clear that it cannot be described in terms of that faith alone, nor can it be protected against decay by correct doctrinal formulae, repeatable rituals or set patterns of moral behavior."
Jürgen Moltmann, The Crucified God, Fortress Press Minneapolis (1993), pg. 18, 19