This question is for non-believers of the Christian faith. All Christians believe that Christ will return. When you hear them say this what do you think it really means?
I see it as connected to the evolution of human consciousness. The return of Christ will be like an updated capacity, that comes with this next aspect of human evolution.
If you look at either science or the Bible, humans were like natural animals at one time; Apes or Adam and Eve in Paradise. They were under natural instinct which are like natural or God given laws, which are designed to allow natural animals to participate in integrated eco-systems. The story of the fall from paradise, is where Adam and Eve choose externally learned knowledge over innate or internal instinct; knowledge. This is the rise of civilization and the loss of paradise and then the perversion of natural human instinct; will and choice.
Jesus is often called the second Adam. He is connected to a return to paradise; heaven. This would be a more advanced state of mind, that can still learn externally, but has that inner sense of natural instinct, that can guide one to the truth. We will still have technology, but a better world view that allows for more cooperation; family of man.
In Revelations, those with no faith or instinct, will not make the cut; update is aborted due to bugs. It might be like having an older computer, from a different era, that cannot be update without some mother board changes, which may not be an easy fix. The update stalls, while others with the proper set up, get the update. Once updated, new capacities appear needed for the future. This leaves behind the last generation and ushers in a new era of the family of man.