I'm still working my way slowly through Chapter 4, which is chock full of insight. Midway through the Pope's dialogue with Rabbi Neusner (and the latter's dialogue with Jesus), Benedict XVI writes:
The proper interplay of Old and New Testaments was and is constitutive for the Church. In his discourses after the Resurrection, Jesus insists that he can be understood only in the context of "the Law and the Prophets" and that his community can live only in this properly understood context. From the beginning, the Church has been, and always will be, exposed to two opposite dangers on this score: on one hand a false legalism of the sort Paul fought against, which throughout history has unfortunately been given the unhappy name of "Judaizing", and on the other hand a repudiation of Moses and the Prophets -- of the Old Testament. This was first proposed by Marcion in the second century, and it is one of the great temptations of modernity. It is no accident that Harnack, leading exponent of liberal theology that he was, insisted that it was high time to fulfill the inheritance of Marcion and free Christianity from the burden of the Old Testament once and for all. Today's widespread temptation to give the New Testament a purely spiritual interpretation, in isolation from any social and political relevance, tends in the same direction.
Conversely, political theologies, of whatever sort, theologize one particular political formula in a way that contradicts the novelty and breadth of Jesus' message. It would, however, be false to characterize such tendencies as a "Judaizing" of Christianity, because Israel offers obedience to the concrete social ordinances of the Torah for the sake of the "eternal Israel's" ethnic community and does not hold up this obedience as a universal political recipe. All in all, it would be good for the Christian world to look respectfully at this obedience of Israel, and thus to appreciate better the great commandments of the Decalogue, which Christians have to transfer into the context of God's universal family and which Jesus, as the "new Moses", has given to us. In him we see the fulfillment of the promise made to Moses: "The LORD your God will raise up for you a prophet like me from among you, from your brethren" (Deut 18:15). (pp. 121f, emphasis added)
I find these words to be a truly theological foundation for what has come to be called the "social teaching of the Church" in the romance languages. While the Judaic religion consists in the obedience (of faith) to the Torah, that obedience to God includes a proper treatment of God's creation and creatures. It both ensures a proper secularity, and safeguards us from falling into a Godless secularism.
I was also happy to see the Pope skewer the word "Judaizing", since the phenomenon the early Christians had to deal with was only circumstantially a function of being Jewish, and Judaism is the religion God founded (originally), and which he practiced as man, and which he fulfilled by taking it to a new level, rather than by abolishing the good in it (which he had inspired).
It seems like the Pope has a jem or two every few pages! It also reads more like Spe salvi
than a "doctrinal letter".