Q. Why was it necessary to have a full ten plagues inflicted upon the Egyptians?A. Perhaps it was to ensure that Egypt would be well and truly broken and that Pharaoh himself would be brought to his knees.
However, the Torah account of the plagues also implies that there had to be a decisive victory over both Egypt and its gods. God says, “I will bring punishment to all the gods of Egypt: I am the Lord!” (Ex. 12:12). Another verse says, “The Lord brought judgment on their gods” (Num. 33:4).
The question is, then, what were their gods? Pinchas Peli draws attention to the fact that the first plague was an attack on the river the Egyptians deified, the Nile; the second, a mockery of the frog goddess, who was said to help women in labour and assist fertility; and so on.
But it is more than this. Pharaoh himself was seen as a god; the sages say the Egyptians thought he never needed to fulfil bodily functions.
The problem when a human ruler or regime has divine pretensions is that they feel they are answerable to nobody; this is why Jewish kings had to carry a Torah scroll with them at all times, to be reminded that they were subject to God’s law. What does that law say? That all human beings are in the Divine image, and a people that degrades and enslaves others has the wrong god.