2,000 years ago Jesus Christ promised “I will come again!”
When Jesus Christ ascended to heaven from the Mount of Olives the angels testified: "This same Jesus, which is taken up from you into heaven, shall so come in like manner as you have seen him go into heaven " (Acts 1:11).
So, as literally and physically as He went to heaven, so He will return.
Links for further reading:
http://www.bexleychristadelphian.org/pmwiki.php?n=Main.LightMagazine
http://www.bexleychristadelphian.org/LightOnBibleProphecy_v2.pdf
The following link has great books to read:
https://yahvehyireh.com/books/
This is my favourite:
https://yahvehyireh.com/books/thine-is-the-kingdom/intro.html