18 Wherefore comfort one another with these words. Well it is a description of an event that will occur when God removes His Church supernaturally from the earth. People will literally disappear as they are called up to the clouds to meed the Lord in the air. There will be one generation that will not know physical death but will be instantly translated into the very presence of the Lord Jesus Christ. At the same time each Christian will also be transformed and receive their resurrection body.
Lets look a bit more closely at the Scriptures previously quoted.
This verse is stating that there will be some alive when Jesus returns. He will be returning with the dead in Christ. That is good news because if you have lost loved ones through death there will be a happy reunion at the rapture. Notice the dead will rise first. There will be a resurrection where we will be given our resurrection, heavenly bodies.