One fundamental truth is that Jesus is returning. The question is not when but how long do we have left? Time is dwindling down, and Christ could step out from Heaven at any moment.
Why do I believe Jesus is returning to planet Earth? I believe because Jesus said so. For those of us who have never seen Jesus physically have the greater faith in knowing that Christ is returning. Even Jesus said blessed are those who have not seen but still believe.
John 20:26-31 A week later Jesus' disciples were again in the house, and Thomas was with them. Even though the doors were locked, Jesus stood among them and said, "Peace be with you!" (27) Then Jesus said to Thomas, "Put your finger here, and look at my hands. Take your hand, and put it into my side. Stop doubting, and believe." (28) Thomas responded to Jesus, "My Lord and my God!" (29) Jesus said to Thomas, "You believe because you've seen me. Blessed are those who haven't seen me but believe." (30) Jesus performed many other miracles that his disciples saw. Those miracles are not written in this book. (31) But these miracles have been written so that you will believe that Jesus is the Messiah, the Son of God, and so that you will have life by believing in him.
Jesus was never proven to be a liar. If He said that He would return, then without a doubt He is returning. Below are Jesus' conversations in regards to His returning.
Luke 12:40 Be ready, because the Son of Man will return when you least expect him."
Matthew 24:42 "Therefore, be alert, because you don't know on what day your Lord will return.
Matthew 24:44 Therefore, you, too, must be ready because the Son of Man will return when you least expect him
Mark 13:35 Therefore, be alert, because you don't know when the owner of the house will return. It could be in the evening or at midnight or at dawn or in the morning.
Acts 15:16 'Afterwards, I will return. I will set up David's fallen tent again. I will restore its ruined places again. I will set it up again
Jesus was so sure of His returning that He warned us to be alert at ALL TIMES. To be alert at all times simply means to stay awake. It means to stay awake to the truth of Christ's return. The moment when we become relaxed and not alert is when Jesus will return. Many Christians will be caught with their pants down. What about you? Are you alert? Are you ready?
Luke 21:32-38 "I can guarantee this truth: This generation will not disappear until all this takes place. (33) The earth and the heavens will disappear, but my words will never disappear. (34) "Make sure that you don't become drunk, hung over, and worried about life. Then that day could suddenly catch you by surprise (35) like a trap that catches a bird. That day will surprise all people who live on the earth. (36) Be alert at all times. Pray so that you have the power to escape everything that is about to happen and to stand in front of the Son of Man."