What exactly do we do on Shavuot? We meditate on the fact that as Jews we have a mission statement, the Torah. The Torah reading, chanted in synagogues on the first morning of the festival's two days, is like a dramatic reenactment of the Sinai revelation. The day has few other mandatory observances, beyond the requirement to refrain from work much as we do on the Sabbath, so as to increase the impact of our contemplation. Many Jews prepare for Shavuot with an all-night Torah study session known as "tikkun leyl Shavuot," intended to demonstrate that unlike our ancestors who stood at Sinai, we are fully prepared to receive God's revelation.

I suspect that this joyous, awe-inspiring, and crucially important day is largely ignored in American Jewish culture because its message makes many contemporary Jews uncomfortable. More than any other festival, it calls us to accept all the ramifications of our commission by God to be Jews-specifically, adherence to the 613 commandments given at Mt. Sinai.

The joys of the eternal Sinaitic covenant ascend to heaven, but the responsibility to follow Jewish law (halakha)-a body of legislation still being clarified and applied by Jewish sages to unprecedented modern circumstances down to our own day isn't compatible with every lifestyle, to put the matter mildly.

As 20th-century Jews entered the dominant culture's mainstream, they found it increasingly difficult to adjust their lifestyles in accordance with the mitzvot. So our grandparents and great-grandparents increasingly shunted Shavuot into obscurity, leaving their descendants-us-Jewishly bereft and impoverished without knowing it.

Jews aren't alone in our misunderstanding of Passover. In this respect we are joined by Christians, among whom the holiday has lately experienced a startling new popularity unknown since the first centuries of the Common Era. Back then, Christian authorities had to warn Christians not to observe Passover the threat of "Judaizing" was considered that severe.

Passover is the Jewish festival that Christianity has sought to take over and adapt as its own. Easter began as the Christian Passover, for good scriptural reasons having to do with the fact that Jesus died at Passover time, and the possibility that his last meal was a Passover seder. Easter used to coincide precisely on the Christian calendar with Passover until Constantine's calendrical reforms. In Christian theology and iconography, Jesus is regarded as the ultimate Passover sacrifice (John 19:36)-Jesus, this man who inspired a religion that gave Jews of his time what some (those who didn't reject him) took to be an honorable discharge from the Sinai covenant.

If Passover is the holiday par excellence that focuses us on the tension between Judaism and Christianity, it also suggests possibilities for resolving the tension. We live in a time of extraordinary Judaizing by Christians, especially among American evangelicals who are bursting with curiosity about Jesus' Old Testament background.

Christians hold seders and read books like Michael Smith and Rami Shapiro's Let Us Break Bread Together: A Passover Haggadah for Christians, Beverly Jeffers's A Christian Observance of Passover, Joan R. Lipis's Celebrate Passover Haggadah: A Christian Presentation of the Traditional Jewish Festival. We seem to be witnessing the emergence of the repressed Christian Passover.

How wonderful it would be if the Christian interest in Passover became an occasion for understanding the holiday's true meaning-a meaning, however, that stands in tension with one of the main teachings of Christianity. The teaching I have in mind holds that through Jesus' death the Jews were somehow freed from the "curse" (as the apostle Paul put it) of the eternal Torah. Passover, in recalling us to the beginning of the process whereby the Jews entered into the Torah covenant, refutes the Christian notion that Torah no longer describes the kind of relationship with the Jews that God wants.

Why should Christians find it "wonderful" to consider an alternative to their own notion that for all people, including Jews, adherence to religious law (as in Judaism) is a lame substitute for a religion of faith (like Christianity)? First of all, Judaism is a religion of faith, albeit one where faith takes concrete expression in the form of the commandments.

But you might still ask what could be so pleasing for a Christian about giving up the idea that faith-entirely and in all cases trumps adherence to law. After all, that idea was at the heart of the apostle Paul's brilliant marketing strategy, and it still pulls in converts two millennia later.

The answer is that for almost 2,000 years, the Christian soul has been haunted by the Jewish problem: what to make of the fact that the Christian savior's own people, who presumably knew him best, rejected him. Didn't the Jews' rejection cast doubt on the Christian assertion that Jesus was the Jewish messiah? Refusal to accept the reasoning behind the Jewish rejection of Jesus has led Christians to devise various tortured theories explaining the mystery of the continuing existence of Judaism and of the Jews, and to the projection of Christian perplexity in the form of anti-Jewish violence in the Crusades, the Inquisition, etc. Christianity is still in need of a scripturally based reconciliation with the special role of Jews in the world, a role defined by Jewish law.

As early as the New Testament's letter to the Hebrews, Christians were quoting the prophet Jeremiah's famous but enigmatic statement that God would "establish a new covenant [brit chadashah] with the house of Israel and with the house of Judah" (Hebrews 8:8 citing Jeremiah 31:31)-as if this pointed to a new law for the Jews (in the form of Christianity) destined to replace that of Sinai.

It pointed to no such thing. In Hebrew, a covenant (brit) designates only the commitment to the content of the agreement between parties, not to the content itself. In other words, the establishment of a new brit only signals that the Jews, in the messianic era, will recommit themselves to the ancient, eternal Sinai covenant. This is why the Torah (Deuteronomy 28:69) speaks of God having established two distinct covenants with the Jews during the 40 years after the exodus from Egypt: one at Sinai, the other in the plains of Moab, where Moses, before he died, recapitulated the teachings the Jews had received from God at Sinai. The content of each covenant was exactly the same. They differed only in the fact that the Jews in each case made a new commitment to observe the same body of law.

The relationship between God and the Jews, with its unique grammar of moral, legal, and philosophical teachings, is eternal and unchanging: This thought, I believe, could set Christian hearts at ease. Yes, there are solid scriptural grounds-notably the linking of the biblical festivals of Passover and Shavuot even for a Christian to believe that the Jewish covenant with God goes on.

Jews could help to spread the word among our Christian neighbors, giving them comfort, correcting the misunderstanding, if only we ourselves understood.