Revelation 12:3

 "Then another portent appeared in heaven: a great red dragon, with seven heads and ten horns, and seven diadems on his heads."

The Wikipedia entry for chapter 12 of Revelation says that the Greek word for dragon appears nine times in the Bible, only in Revelation. Over and over again throughout history when Christianity has conquered paganism the gods of the prior culture are portrayed in artwork as, or referred to as, dragons. 

Revelation 12:13-14

 ¹³ So when the dragon saw that he had been thrown down to the earth, he pursued the woman who had given birth to the male child. ¹⁴ But the woman was given the two wings of the great eagle, so that she could fly from the serpent into the wilderness, to her place where she is nourished for a time, and times, and half a time.

 

Verse 13 seems to be telling us that since Lucifer has been cut off or separated from God and thrown out of heaven he now makes it his focus to pursue the church, which is what the woman in the text is said to symbolize, whether this be a reference to Jews or Christians or both.