The Catechism in Questions & Answers

560. What is the basis of the believers’ hope that they will not need to suffer physical death?

The hope of the believers that they will not have to suffer physical death is based on the statement of Apostle Paul: “For in this we groan, earnestly desiring to be clothed with our habitation which is from heaven. [...] For we who are in this tent groan, being burdened, not because we want to be unclothed, but further clothed, that mortality may be swallowed up by life. Now He who has prepared us for this very thing is God, who also has given us the Spirit as a guarantee” (2 Corinthians 5: 2, 4-5).
With the word “habitation” the Apostle is referring to the glorious body which will not only be received by those who resurrect from the dead, but also by those who are to be transformed at the return of Christ: The expression “further clothed” means to receive a new body without having to die beforehand. Here “unclothed” is an expression for dying.