1 Cor 15:51–52. “Behold, I tell you a mystery; we will not all sleep, but we will all be changed, in a moment, in the twinkling of an eye, at the last trumpet; for the trumpet will sound, and the dead will be raised imperishable, and we will be changed.”
I talked about the mystery that Paul mentions of the last generation that will not have to die to receive their new bodies. This is a different, though related, event to the rapture.
The “twinkling of an eye” expression refers to the translation of the bodies of believers who are alive at the second coming of Christ.