The Antichrist slays the Two Witnesses, and the Trib period now begins its second half. The Antichrist then goes after God's people in a massive persecution that will permit no worship except to him. It says in Scripture of this time (i.e., the second half of the Trib):

"I kept looking, and that horn [i.e., Antichrist] was waging war with the saints and overpowering them." (Daniel 7:21)

"...and they will be given into his hand for a time, times and half a time." (Daniel 7:25b)

"There was given to him a mouth speaking arrogant words and blasphemies, and authority to act for forty-two months was given to him." (Revelation 13:5)

"It was also given to him to make war with the saints and to overcome them and authority over every tribe and people and tongue and nation was given to him." (Revelation 13:7)