Rosenzweig locates a fundamental similarity between Judaism and Christianity in their mutual affirmation of protology and eschatology, which give form and meaning to the “middle things” that occur between A and B - that is, the middle things of world history. Rosenstock objects that the two are not equal simply “because they both touch the same endpoints.” The shape of the path between A and B is crucial (Judaism Despite Christianity: The 1916 Wartime Correspondence Between Eugen Rosenstock-Huessy and Franz Rosenzweig, 155).
Rosenstock adds a remarkable contrast of Judaism and Christianity, and an equally remarkable calendrical description of Christian experience:
“over against the calm certainty of the Synagogue, we have the perilous adventurous character of our pattern of life, which tears apart the course of the year and of his own life, lays on the heart of each man his own Sabbath and his own ‘Four,’ his particular cross, absolves him from Cohen’s and Kant’s ‘love for the remotest,’ and leaves him only the love for his neighbor. It sets in the Church’s year the reconciliation of this violent disruption of the calendar of the secular year and of one’s own inner life, by pointing to the wandering of the Lord on earth as the far distant goal, and also by making the condition that we work out for ourselves through the vita imitative this stormy masterful life of ‘the’ man of Christ, in that he himself then lives his year in us. Without this cultivation of the new man, Sunday is merely bourgeois, a mere Old Testament Sabbath for Christians - that is to say, nothing.”
He returns at the end of the letter to the contrast of “eternal Jew” and the church as “eternal community”: “in the program, viewed abstractly, there is identity; but, starting from the same point, the opposition between the two religious patterns is bound to become continually sharper as they go forward. The ‘eternal Jew’ as a horizontal two-dimensional interest in religion, and Time is bound up in him, and it is, as it were, always being fulfilled just because it is never fulfilled. The ‘eternal community’ has a vertically directed impulse. Because it strives in every moment to behave as if it were worldwide, because even the individual Christian is almost as the whole body, and the microcosm and the God-man is taken seriously, so its longing turned towards Time, towards the discerning and fulfilling of epochs” (155-6).