Do we know when the Lord is coming back?

No one truly knows when the rapture is going to take place, or the end of time in general (Matthew 24:36).  However there are things within the Bible to show us that the time is drawing near.  First there will be a falling away from the faith of Christ (2 Thessalonians 2:3) and no one will believe or even listen to sound doctrine (2 Timothy 4:3).  Mankind will become exceedingly more sinful (2 Timothy 3:1-7) and those who believe in the Bible and are truly saved will be persecuted and hated (John 15:20).  Even though we do not know when Jesus is going to come back we need to always be ready for His return at any moment and to continue to follow Him and to try to reach others for Him (Romans 13:11-12).