1 Corinthians 15:51

"Behold" or "Listen" grabs the reader’s attention and announces something important. Paul was about to explain something never before revealed, a mystery (Gr. mysterion; cf. Matthew 13:11; Romans 11:25; Romans 16:25; 1 Corinthians 2:7; 1 Corinthians 4:1; 1 Corinthians 13:2; 1 Corinthians 14:2; Ephesians 1:9; Ephesians 3:3-4; Ephesians 3:9; Ephesians 5:32; Ephesians 6:19; et al.). He had previously written that at the Rapture dead Christians would rise before God will catch living Christians up to meet the Lord in the air (1 Thessalonians 4:15-17). He had just revealed that resurrection bodies will be different from our present bodies: spiritual rather than natural (1 Corinthians 15:35-39). Now he revealed that living believers translated at the Rapture would also receive spiritual bodies. Three key New Testament passages that deal with the Rapture are John 14:1-3, 1 Corinthians 15:51-53, and 1 Thessalonians 4:13-18.

Not every Christian will die before he or she receives a new body, but every one must experience this change, even the "spiritual" Corinthians. Whether we are alive or dead when the Rapture takes place we will all receive spiritual bodies at that moment. "All" negates the doctrine of the partial rapture of the church, the view that only watchful Christians will participate in the Rapture.