Adam Clarke on 1 Corinthians 15:50

Flesh and blood cannot inherit the kingdom - This is a Hebrew periphrasis for man, and man in his present state of infirmity and decay. Man, in his present state, cannot inherit the kingdom of God; his nature is not suited to that place; he could not, in his present weak state, endure an exceeding great and eternal weight of glory. Therefore, it is necessary that he should die, or be changed; that he should have a celestial body suited to the celestial state. The apostle is certainly not speaking of flesh and blood in a moral sense, to signify corruption of mind and heart; but in a natural sense; as such, flesh and blood cannot inherit glory, for the reasons already assigned.