What does 1 Corinthians 15:51 mean when it says “we will all be changed”?

What does 1 Corinthians 15:51 mean when it says “we will all be changed”?

Dr. John Ankerberg: What does the word “changed” mean? The Greek word allasso is translated “to be changed” or it literally means “to be transformed.” Believers who are alive will instantly be given new bodies, that is, spiritual bodies like the Lord Jesus. How long will it take? The Bible says “in a moment, in the twinkling of an eye.” How long will the Rapture event take? Well, we’re going to be changed instantaneously. Someone has said that the blinking of an eye is about one-thousandth of a second. But that’s too long. The Greek word is atomos from which we get the word atom. It actually means something that is so small, it’s a period of time that cannot be divided any further. The Rapture will occur so quickly and suddenly that the time frame in which it occurs cannot be humanly divided. In a flash of a second, every living believer on earth will be gone. Suddenly, without warning, only unbelievers will be populating planet earth because of the Rapture.