According to Revelation 12:9 this dragon is in fact “that ancient serpent, who is called the devil and Satan, the deceiver of the whole world.” This is an obvious reference to the serpent of Paradise, which instigated the fall into sin. That begs the question: why does John see a dragon instead of a serpent? A dragon (only known through mythology, not from natural science) is a more threatening and ominous creature than a snake. With the term “dragon” the Lord exposes the true character of the “cunning” serpent of Genesis 3:1–24. Already in Isaiah 27:1 the Lord had used the term “dragon” (known from mythological lore around Israel) to denote that the serpent was in fact dangerous and vicious. The present passage is built on that verse.
3 And another sign appeared in heaven: behold, a great red dragon, with seven heads and ten horns, and on his heads seven diadems.