How can the church and the kingdom be the same when the Bible says flesh will not enter the kingdom?

Answer:

"Now this I say, brethren, that flesh and blood cannot inherit the kingdom of God; nor does corruption inherit incorruption" (I Corinthians 15:50).

In this context, Paul is speaking of life after death. He argues that we will have new, spiritual bodies and not physical bodies after death. "It is sown a natural body, it is raised a spiritual body. There is a natural body, and there is a spiritual body" (I Corinthians 15:44).

That Paul was discussing heaven is also seen in his use of the word "inherit." "In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise, who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory" (Ephesians 1:13-14). When we become Christians, we are declared to be children of God and have a promise of inheritance with God in heaven. "For you are all sons of God through faith in Christ Jesus. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus. And if you are Christ's, then you are Abraham's seed, and heirs according to the promise" (Galatians 3:26-29).

Thus, we are still speaking of God's called-out (the church), but we are referring to the time when the church enters heaven. The kingdom is just another term for the same group of people, seen from a different perspective. Where "church" speaks of the people who respond to God's call to come out of the world and to assemble as His people, the word "kingdom" sees these same people as citizens of a nation ruled by Christ. "But you are a chosen generation, a royal priesthood, a holy nation, His own special people, that you may proclaim the praises of Him who called you out of darkness into His marvelous light" (I Peter 2:9).

The kingdom is not reserved as a future term. "He has delivered us from the power of darkness and conveyed us into the kingdom of the Son of His love, in whom we have redemption through His blood, the forgiveness of sins" (Colossians 1:13-14). Notice the past tense. When we are saved, we enter the kingdom. Just a few statements later Paul said, "And He is the head of the body, the church, who is the beginning, the firstborn from the dead, that in all things He may have the preeminence" (Colossians 1:18). Paul hadn't changed topics. To Paul being in the kingdom and in the church was the same thing.