Remember, too, that Jesus initiated this observance and then died on the Jewish calendar date of Nisan 14.a That was the day of the Passover, a festival reminding the Jews of the great deliverance they had experienced in Egypt in the 16th century B.C.E. At that time, the sacrifice of a lamb resulted in the salvation of the Jewish firstborn, whereas Jehovah’s angel struck down all the firstborn of Egypt.​—Exodus 12:21, 24-27.

How does this help our understanding? Well, the Christian apostle Paul wrote: “Christ our passover has been sacrificed.” (1 Corinthians 5:7) Jesus’ death was a greater Passover sacrifice, giving mankind the opportunity for a far grander salvation. For Christians, therefore, the Memorial of Christ’s death has replaced the Jewish Passover.​—John 3:16.

The Passover was an annual celebration. Logically, then, so is the Memorial. The Passover​—the day Jesus died—​always fell on the 14th day of the Jewish month Nisan. Hence, Christ’s death should be memorialized once a year on the calendar day that corresponds to Nisan 14.