Observe it at the time required—in the evening after sunset on the fourteenth day of this month, and do so in accordance with its rules and regulations.”
On the fourteenth day of the second month they killed the Passover lamb. The priests and Levites were ashamed, and they purified themselves and brought burnt offerings to the Lord's Temple.
Otherwise Christ would have had to suffer many times since the creation of the world. No: just this one time at the end of the present age he came to remove sin by sacrificing himself.