Martin Buber once expressed, with profound insight, a dynamic that is at the heart of the tension between Judaism and Christianity:
“Now to the Christian, the Jew is the incomprehensibly obdurate man, who declines to see what has happened; and to the Jew, the Christian is the incomprehensibly daring man, who affirms in an unredeemed world that its redemption has been accomplished.” (Martin Buber, “The Two Foci of the Jewish Soul,” in Israel and the World: Essays in a Time of Crisis, pp. 28-40)
While not citing Buber directly, Gerhard Lohfink is one of the only Christian writers I have come across who not only acknowledges the truth of Buber’s implicit critique of Christianity, but who is also willing to respond on its own terms. What an incredible challenge to every generation of Christ-followers, until the end of the world:
“The Jews argue quite correctly that if nothing in the world has been changed, the Messiah cannot have come…This Jewish objection must be taken very seriously. It is the strongest objection there is against Christianity. It strikes the innermost nerve of Christian faith. As we have seen, the [early church] Fathers evidently took the objection quite seriously. It is above all important that they did not dispute its premises. They agreed completely with Judaism that the world must really be changed when the Messiah comes.
The reply of the early church Fathers to the central Jewish objection to Christianity is not that the world need not be changed, since redemption takes place invisibly ; nor is it that redemption will not occur until the end of the world. Their answer is rather that the Messiah has come and that the world has in fact changed. It has been transformed in the Messiah’s people, which lives in accord with the law of Christ…
It must be obvious that this answer is quite risky. It endangers the whole of Christology if one day the reality of the church contradicts it…But the early church Fathers did not follow the harmless, safe path. They insisted that the new worship of God, the new manner of life, the new creation already had visible and tangible effects in the church…
How can the Messiah have come if nothing in the world has changed? Examined more closely, this is not only the basic question of Jews. Every non-Christian raises a similar question. How can you speak of redemption if nothing in the world has changed since the coming of your redeemer? For this reason, the truth of Christian faith can shine only when it is intelligible through the praxis of Christians. The ancient church, filled in this respect as in others with biblical sobriety, recognized this connection clearly. It knew that it had to be a sign of the truth of the gospel in its entire existence. The astonishing growth which it experienced in a relatively brief period can only be explained through the radiance of that sign…
The twelve apostles preached the gospel in the whole world and established a sufficient number of local churches. This marked the conclusion of mission in the strict sense. The communities established by the apostles existed from then on as signs of the truth. Pagan society was then in a position to choose. This was in principle the whole missionary theory of the ancient church. A strict distinction was made between the specific and unique missionary charge of the apostles and the task of symbolic presence incumbent upon all churches. Obviously this did not exclude missionary activity in the period which followed the apostles. But it is evident ‘that Christianity in the pre-Constantinian age achieved its astonishing growth simply through its presence and notability, not through organized missionary efforts.’ A great and unshakeable confidence that Christian praxis will itself convince others permeates the writings of all the Apologists [he cites a number of relevant passages in the pages that follow]…
Evidently the ancient church saw a much stronger connection between the symbolic character of the church and Christology than we do today. The true nature of Christ can shine forth only when the church makes visible the messianic alternative and the eschatological new creation which have taken their place in the world since Christ.” (Gerhard Lohfink, Jesus and Community, pp. 175-79)
[UPDATE: “The story is told of a wise old Jewish rabbi who was informed that some say that the Messiah had already come. He made no answer but went to the window, opened it, and looked out into the world. After a moment he turned and sadly shook his head. If the Messiah had in fact come, things would have been different, but in fact nothing had changed.” (Jerome Murphy-O’Connor, Becoming Human Together, p. 9)