That's true about many New Testament references. When John the Baptist hails Jesus as the "Lamb of God," he's signaling that it will be Jesus, rather than the lamb, who will be sacrificed to take "away the sins of the world." It's important to keep in mind the world that the writers of the books of the New Testament were living in. Rabbi Hillel, referred to in the Haggadah, was a renowned teacher and scholar, someone whose somewhat liberal ideas certainly would have influenced Jesus and his followers. Hillel's grandson, Rabbi Gamaliel, also mentioned in the Seder service, was Saint Paul's teacher, something Paul advertised to prove his credibility as a good Jew. In the Acts of the Apostles we hear him tell a crowd in Jerusalem, "As a pupil of Gamaliel I was thoroughly trained in every part of our ancestral law." And for Paul the passover tradition of cleaning leavening agents out of the house provides a repeated metaphor. He tells the Corinthians to "Get rid of the old leaven and then you will be a new batch of unleavened dough. Indeed you already are, because Christ our Passover lamb has been sacrificed. So we who observe the festival must not use the old leaven, the leaven of depravity and wickedness, but only the unleavened bread, which is sincerity and truth." The idea of cleaning out the "leaven" of sin before the redemptive feast finds its way into many cultures. The Greeks do their "spring cleaning" on the first Monday of Lent, called Kathara Deftera. The children go fly kites while the women scrub the houses and the men whitewash them in preparation for Easter. It takes a little longer—the forty days of Lent—for soul scrubbing.
Living in Greece, an ancient country so close to the Holy Land, constantly reminded us how tightly the Jewish and Christian traditions were intertwined. In fact, the Greek word Pascha means both Passover and Easter, and it's the most important time of the year in the Orthodox Church. One year we took the children to the Easter midnight liturgy at Saint Sophia, our local church. The entire place was pitch black until a priest lit a single candle and announced, "Christos anesti," "Christ is risen." Gradually, the flame was passed from hand to hand, filling the old stone structure with eerie light. Then we walked home, still carrying our burning candles, and followed the custom of making a sooty cross above our front door. It's clearly a ritual taken directly from the Exodus story, when Jews in Egypt marked their doorways with the blood of the lamb to alert God to "pass over" their houses as he carried out the most terrible of the Ten Plagues, the slaying of the firstborn.