Jean,

Extremely interesting!

That difference in their calendar traditions, clearly explains, what some have incorrectly thought was a mistake in the Bible:

John 18:28 Then led they Jesus from Caiaphas unto the hall of judgment: and it was early; and they themselves went not into the judgment hall, lest they should be defiled; but that they might eat the passover.

John 19:14 And it was the preparation of the passover, and about the sixth hour: and he saith unto the Jews, Behold your King!

As you showed, Jesus and his disciples ate the Passover after sundown the 14th, but the priests were going to eat the passover after sundown the 15th.

Apparently the priests didn't mind people bringing lambs to the temple to be killed on the two days, instead of only one.

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