The dead in Christ were to sleep in Jesus until His Return at which time they were to be resurrected. From the Return of Christ onward, the one who lives in Christ is changed into his own spiritual body when Christ, the Shepherd and Bishop of our souls, comes to receive him and the man’s natural body is left behind like old clothing.
1Co 15:51-52a Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed, 52 In a moment, in the twinkling of an eye.
1Jn 3:2 Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is.