What is the truth behind these sayings (1 Corinthians 15:50)?

Our sinful flesh and blood cannot inherit God's Kingdom-it is perishable. One must be made alive in the Spirit as Jesus was. The apostle Paul declares that “if there is a physical body, there is also a spiritual one.” (1Co 15:44) This is corroborated by the apostle Peter when he tells persons of fleshly, human nature, called to be joint heirs with Christ, that they are to become partakers of “divine nature,” namely, spirit life in the invisible heavens. (2Pe 1:4) This requires a change in organism, for “flesh and blood cannot inherit God’s kingdom, neither does corruption inherit incorruption.”—1Co 15:50-54.