"Now whenever you may be perceiving the abomination of desolation, declared by Daniel the prophet, standing where it must not (let the reader apprehend), then let those in Judea flee into the mountains...for in those days will be affliction such as has not occurred from the beginning of creation which God creates until now." (Mark 13:14-20)
The world leader who authorizes the abomination is called a wild beast in the book of Revelation but most people refer to him as the Antichrist. He will peacefully come to world power by the middle of the Tribulation with the help of another wild beast called the False Prophet. Apparently he will be a famous religious leader.
"For God has not appointed us to suffer wrath, but to obtain salvation through our Lord Jesus Christ. He died for us so that, whether we are awake or asleep, we may live together with Him. Therefore encourage and build one another up, just as you are already doing." (1 Thessalonians 5:9-11)
"Then I saw heaven standing open, and there before me was a white horse. And its rider is called Faithful and True. With righteousness He judges and wages war. He has eyes like blazing fire, and many royal crowns on His head. He has a name written on Him that only He Himself knows. He is dressed in a robe dipped in blood, and His name is The Word of God. The armies of heaven, dressed in fine linen, white and pure, follow Him on white horses. And from His mouth proceeds a sharp sword with which to strike down the nations, and He will rule them with an iron scepter. He treads the winepress of the fury of the wrath of God the Almighty. And He has a name written on His robe and on His thigh: King of kings and Lord of lords."(Revelation 19:11-16)