The Bible tells us that our Lord Jesus Christ is coming back a secod time.  
Hebrews 9:28

“so Christ was sacrificed once to take away the sins of many people; and he will appear a second time, not to bear sin, but to bring salvation to those who are waiting for him”.

This is the glorious hope that every Christian has; our Lord will come back for us.

Matthew 25:13

 "Therefore keep watch, because you do not know the day or the hour.”

Even when we do not know when He’ll be returning, the Lord tells us in Luke 12:40 to be ready, because the Son of Man will come at an hour when we do not expect him."