Christian observances of Jewish holidays (Yamim Tovim) is a practice evidenced since the time of Christ. Specific practices vary among denominations: these holidays may be honored in their original form in recognition of Christianity's Jewish roots or altered to suit Christian theology. Symbolic and thematic features of Jewish services are commonly interpreted in a Christian light: for example, the Paschal Lamb of the Passover Seder is viewed as a symbol of Christ's sacrifice.