This is a very tough question because the beast of Revelation (chapter 13) has been under much debate over the centuries. Read the entire chapter in your Bible or HERE.
In this chapter, there are 2 beasts described. The first beast was a monster having 7 heads & 10 horns (each horn with a crown). On each head, the writer of Revelation, John, saw a name that blasphemed against God (v. 2). This beast was also "given authority over every tribe, people, language and nation" and they worshipped him (v. 7-8). In verse 3, we learn that one of the beast's heads suffered a "fatal" wound form which it was healed, and in turn, the world "marveled" at it. Lastly, we learn that the beast was "was allowed to make war on the saints and to conquer them," (v.7) i.e. it persecuted Christians.
This first beast derived its power from the dragon - the 2nd beast of Revelation 13. This 2nd beast is, in fact, the devil or Satan (Read Revelation 12:7-8, where Satan is described as a "dragon": "Now war arose in heaven, r Michael and s his angels fighting against the dragon. And the dragon and his angels fought back, but he was defeated, and there was no longer any place for them in heaven.").
What does this all mean?
First, let us understand why John wrote Revelation: "The original purpose of Revelation 13 was to show the Christians of Asia that the Roman Empire and the worship of the emperor and local deities was not of God. There was no point of compromise between this Babylon the Great and the people of God. The churches were warned that a time of persecution over these issues would befall them. The members were to stand fast in the faith of Christ, their slain Lamb, even if it led them to their death. In death or martyrdom they would witness to the fact that a greater than Caesar was alive, Jesus the Alpha and Omega. In the end, the church would win and the martyrs would reign with Christ as priests and kings"
[see the full article HERE].
Second, if you read articles or books, you'll find various opinions from various people. Some have identified the first beast as the Roman Empire of the 1st Century. The Roman Empire considered itself to be kind of savior to the world and thus, expected to be worshipped - which actually happened as many citizens bowed to the emperor and considered him to be a god. Additionally, the Roman empire persecuted the church. Some even suggest that Nero, one of the Roman emperors at the time, is the "wounded head of the beast" (13:3) as he committed suicide in the late 60 AD.
Others hold a completely different perspective, namely Revelation 13 is future prophecy. They identify the first beast will rule the world using a world government much like the Roman Empire of the 1st Century. He is what the Apostle Paul calls the "man of lawlessness" (2 Thessalonians 2:3) and will rise to gain much global attention, but also horrifically persecute Christians.
So now what? A few important notes here:
1. To claim that a specific time in history is when the events of Revelation 13 goes beyond what the writer of Revelation, John, intended. We do not and cannot known when specific events of the last days will happen (Matthew 24:36).
2. The only thing Scripture tells us is that though the beasts of Revelation (i.e. Satan and his demon minions) continue to influence and dominant the world, he can never dominate the Christian, even if he takes away our earthly lives:
And authority was given it over every tribe and people and language and nation, and all who dwell on earth will worship it, everyone whose name has not been written before the foundation of the world in the book of life of the Lamb who was slain (Revelation 13:7-8)
3. The good news is that Jesus Christ is greater than the Satan. His plans of redemption will not be stopped or delayed. One day in the future, God will judge Satan - the beast/dragon of Revelation (see Revelation 20:2) and those that rebel against him (Revelation 20:15).
Hope this answer clarifies things a bit. Keep the questions coming. We're trying our best!
[Answered by Pastor HM]