Your question, What does it mean that the devil's time on earth will be short in Revelation 12:12?
This concept originates from Jesus’s statement about shortening time for the sake of the elect.
Matthew 24:22 “And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened.”
How much time is shortened for the sake of the elect? This is explained in Revelation.
At the sounding of the fourth trumpet we see the following.
Revelation 8:12 “And the fourth angel sounded, and the third part of the sun was smitten, and the third part of the moon, and the third part of the stars; so as the third part of them was darkened, and the day shone not for a third part of it, and the night likewise.”
This means the duration of a day is reduced to eighteen hours instead of the usual twenty-four.
After the shortening of time, Jesus prophesied the coming of the false Christ.
Matthew 24:23 “Then if any man shall say unto you, Lo, here is Christ, or there; believe it not. For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect.”
Hope this answers your question.
