Signs of the times
"Now, brethren, concerning the coming of our Lord Jesus Christ and our gathering together to Him, we ask you, not to be soon shaken in mind or troubled, either by spirit or by word or by letter, as if from us, as though the day of Christ had come.
"Let no one deceive you by any means; for that Day will not come unless the falling away comes first [apostasy], and the man of sin is revealed, the son of perdition, who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the temple of God, showing himself that he is God....
"For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way."
2 Thessalonians 2:1-7
To prepare His people for future events, Jesus told His disciples,
"Now learn this parable from the fig tree: When its branch has already become tender and puts forth leaves, you know that summer is near. So you also, when you see all these things, know that it is near... Watch therefore...." Matthew 24:32-33, 42