A.T. Robertson Commentary 1 Corinthians 15:50

"Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; neither doth corruption inherit incorruption." — 1 Corinthians 15:50 (ASV)

Cannot inherit (κληρονομησα ου δυναντα). Hence there must be a change by death from the natural body to the spiritual body. In the case of Christ this change was wrought in less than three days and even then the body of Jesus was in a transition state before the Ascension. He ate and could be handled and yet he passed through closed doors. Paul does not base his argument on the special circumstances connected with the risen body of Jesus.