Verse 12 [of Ex. 12) tells us that the judgment of Yahweh is not only on the Egyptians but also on their deities. This is probably an allusion to the fact that Egyptians would often pray for the safety of their firstborn, particularly firstborn sons, as was the custom in many ancient patriarchal cultures. The death of the firstborn would be seen as a sign of the anger or perhaps the impotence of their gods. This is worth pondering when it comes to the death of Jesus as God’s only begotten, or beloved, Son. Would Jesus’ contemporaries have assumed his death was a manifestation of God’s wrath? Probably so. In any event, Yahweh is showing his superiority over the spirits behind the pagan deities, and thus we should not overlook the supernatural struggle that is implied to be behind the contest of wills between Moses and Pharaoh.
Ben Witherington III, Making a Meal of It: Rethinking the Theology of the Lord's Supper
egyptians, exodus, firstborn, jesus, pagan-deities, plagues