Question: How did 666 become the devil's number?

Easy. It is written...

Revelations 13:11 " And I beheld another beast coming up out of earth, and he had two horns like a lamb, and he spake like a dragon"

Several verses later...

And here is wisdom. Let him that have understanding count the number of the beast: for it is the number of a man
and his number is six hundred threescore and six.


Given this edict by the Book of Revelations you can understand why Christians would like to tie this number (666) to -the man, -the beast, -the Antichrist, -the False Messiah.