The Ten Plagues upon Egypt all proved to be a judgment against the gods of Egypt, especially the tenth, the death of the firstborn.
The death of the firstborn resulted in the greatest humiliation for the Egyptian gods and goddesses. (Ex 12:12) The rulers of Egypt actually styled themselves as gods, the sons of Ra, or Amon-Ra. It was claimed that Ra, or Amon-Ra, had intercourse with the queen. The son born was, therefore, viewed as a god incarnate and was dedicated to Ra, or Amon-Ra, at his temple. Hence, the death of Pharaoh’s firstborn, in effect, actually meant the death of a god. (Ex 12:29) This in itself would have been a severe blow to Egypt’s religion, and the complete impotence of all the deities was manifested in their being unable to save the firstborn of the Egyptians from death.