Yes he was given power for 42 months to persecute and kill the Jews and Christians, and the Lord comes back at the end of the 42 months (1,260 days)(3 1/2 years).
He will be in power for those 3 1/2 years of the great tribulation and the false prophet (2nd beast) will force others to worship him (1st beast) during this time.
This once again is where the similarity to the Roman empire comes into play, because the Roman empire had two leaders; one being the political leader and the other was the religious leader.
Whaaaaat? The Roman Empire had one leader who was called Caesar....He was god! So what leader could be compared to Augustus or Nero or Julius?????? Hadrian or Vespian????