The body we have in the spiritual world is not the body that we put into the grave. The Bible says that our physical body is corruptible and mortal, which means that it does not last, but rots and dies. "Flesh and blood cannot inherit the kingdom of God; neither does corruption inherit incorruption" (1 Corinthians 15: 50). "We brought nothing into this world, and it is certain we can carry nothing out" (1 Timothy 6:7). When we go to our eternal home "then the dust will return to the earth as it was, and the spirit will return to God who gave it" (Ecclesiastes 12:5, 7; compare Genesis 3:19). So our earthly body cannot go to heaven, but when we put off our physical body, our corruptible and mortal life is changed into an incorruptible and immortal life (1 Corinthians 15: 53-54). Evidently when Paul said this, some people were wondering if everyone would sleep a long time in the grave before the resurrection, for Paul reassures people that we will not all sleep, and that it will not take ages but will happen immediately, in the twinkling of an eye, at the last trumpet, that is, when we die.