Blasphemy and False Worship
The beast in this vision is a global ruler or coalition of rulers who will be inspired by Satan and his hatred of Jesus and His people. The Lord will allow the beast to express its deepest motivation (Matthew 12:34). In that way, when there is the final conflict with Satan and his empire, everybody will know that this is not a political contest, or a matter of cultural identity, but it will be all about Jesus the King and the world's refusal to submit to Him (Revelation 19:19-21). God's judgement will be seen to be just, and His vindication of His people will be complete (Jeremiah 9:23-24).
And so, the beast will be given a mouth to speak too well of itself and to speak blasphemy against Jesus. It will boast of its abilities and what it has achieved; it will proudly assert its power and draw enthusiastic admiration and worship from the people in the world. It will present Father God as being nothing and Jesus as being irrelevant, as well as blaming God for the evil in the world. It will ridicule heaven, and mock believers who have died, including the martyrs. But none of this is outside of God's control (Acts 2:23-24): He will allow this leader to express his hatred, just as the crowd shouted for Jesus to be crucified (Mark 15:13-20).
This beast will, for a short period of time, violently attack the church, isolating them from the rest of society and punishing them for belonging to Jesus. The rest of the world will praise this beast and willingly submit to all its demands. It will bring in a new world order which will try to unify everybody against the Lord Jesus Christ. However, all who love Christ, and know that they have been ransomed by Him out of the world and its corruption, will not bow to this global dictator. They will refuse to deny that Jesus is Lord and, like the believers alive when John was writing, some will be killed for rejecting this leader's demands (Revelation 20:4). But they know they are eternally safe; their names are written in the Lamb's Book of Life (Revelation 21:27).
This is no new thing, in essence (Psalm 2:1-2). Throughout history, God's people have come under pressure to conform to the world and agree with the devil. The pages of history are littered with persecutions, exiles and martyrs. Some of that is happening today. What will be new is the scale and the unrestrained nature of the new world order in its overt hatred of everything which is of Christ. In God's mercy, the duration of this evil reign will be short. But by then, everybody will know how evil, evil is; and God's people will seek justice from Him (Proverbs 28:5). Until then, like the foreshocks which precede the massive earthquake, we already see new attempts at establishing antichrist leadership with its accompanying persecution. But the believer must simply hold on in faith until Jesus returns (Hebrews 3:12-14; Revelation 3:11).