One of the greatest signs regarding the end of the age is what Paul referred to as the "falling away" or the "last days" apostasy [the rejection/defection/abandonment of God].

"Let no one deceive or beguile you in any way, for that day will not come except the [a]apostasy comes first [unless the predicted great [b]falling away of those who have professed to be Christians has come], and the man of lawlessness (sin) is revealed, who is the son of doom (of perdition). 2 Thessalonians 2:3

The Greek word apostesia means the falling away or apostasy that occurs before the revealing of the anitchrist.