Humans generally hope for immortality and project it into improbable gods that bring improbable after-life worlds.
My idea is that extremely capable beings from the future could come back into whatever present to distort reality as we know it and to give continuity where it isn't (extend life).
Technically it would be more like a Google crawler that extends outside the boundaries of the Internet and time. Given enough science and technology, an extremely powerful computer could have the ability to cope with the crawling and possibly branching distortions (miracles) of such an extensive domain.
About the concept of miracles. I think that they are possible to some exent. Assuming that physical rules at some very low level can be distorted, our brain's is still very gullible. Much more than we'd like to admit.
I remember some studies with spectators watching a short movie, where the actors would have completely different shirts between shots. The subjects of the research would not notice the change of shirts between shots. This is the very essence of illusionism.. as long as things can't be scientifically analyzed.. otherwise illusionism as we know it is not possible.. but could still be possible at any level lower than the measuring tools and knowledge of the people involved.
The "back to the present" concept is very real even nowadays as more and more people are leaving traces on the Internet.. that's a lot of readily accessible material for posterity there !