7:3 harden Pharaoh’s heart. This sovereign act of God, designed to make His power known (see Romans 9:17) might seem cruel except that Pharaoh volitionally hardened his own heart against God (e.g., Exodus 8:15), and so fully merited God’s judgment. Here is a succinct example of the great mystery, inscrutable to our finite minds, of God’s election versus man’s will. Like two sides of the same coin, both are real but can only be viewed and understood separately.
7:3 my wonders. The notorious ten plagues of Egypt were used by God to bring about the exodus of His people from their long years of slavery in Egypt. Skeptics have argued that each of the phenomena associated with the plagues was a natural occurrence commonly experienced during the course of a year in ancient Egypt, except that it was more intense than usual. Even if that were so, their activation just at the command of Moses, as well as the sharp discrimination of many of the plagues, as they affected only the Egyptians, make it certain that they were divine miracles. Furthermore, each of them seemed specifically designed to undermine the faith of the Egyptians in one of their pagan gods. The fact that it has been difficult to identify this period of severe judgment on Egypt in secular records is attributable to one or both of the following factors: (1) it was the practice of ancient kings only to record their triumphs on permanent monuments, not their times of ignominy and defeat; (2) Egyptian chronology is still very controversial, with several schools of thought; there are at least two periods in Egyptian history that might correlate well with the Exodus, once the chronology has been settled.
7:12 they became serpents. Like the “image of the beast” (Revelation 133–15), which will seem to have life, these magician-induced serpents can only have been “lying wonders” (II Thessalonians 2:9). Neither men nor demons can create life; this is a prerogative only of God, who “created...every living creature” (Genesis 1:21). However, men and demons can generate hypnotic mental states and visions which people like Pharaoh may think involve real physical entities. When it was over, however, there was nothing to show for it; even the rods were gone.
7:17 turned to blood. This may not imply literal blood but rather “turned to appear like blood” Similar language is used in Joel 2:31, which speaks prophetically of God turning “the moon into blood.” See also II Kings 3:22, which says “the Moabites saw the water...as red as blood.” Whatever chemical or biological change took place, it made the water undrinkable and lethal even to the fish in the rivers. During the seven days that the plague persisted, the people had to dig for groundwater, from which the lethal contents of the water had apparently been filtered out (Exodus 7:24-25). One effect of this plague surely was that of undermining the Egyptian’s faith in their various river deities, especially Hapi, who personified the Nile.