Jehovah’s Witnesses love to use 1 Corinthians 15:45 to make their case Jesus resurrected spiritually because He is a “life-giving spirit.” Let’s read the passage in context: 1 Corinthians 15:45-50 “So also it is written, ‘The first MAN, Adam, BECAME A LIVING SOUL.’ The last Adam became a life-giving spirit. 46 However, the spiritual is not first, but the natural; then the spiritual. 47 The first man is from the earth, earthy; the second man is from heaven. 48 As is the earthy, so also are those who are earthy; and as is the heavenly, so also are those who are heavenly. 49 Just as we have borne the image of the earthy, we will also bear the image of the heavenly. 50 Now I say this, brethren, that flesh and blood cannot inherit the kingdom of God; nor does the perishable inherit the imperishable.”
In parts two and three I made a strong case Jesus rose from the dead bodily. Verses 15:42-44 I argued the Greek word for body (soma) when referencing a person was always a physical body. Greek scholar Robert Gundry in his authoritative book Soma in Biblical Theology affirms this conclusion. In 1 Corinthians 15:44 I showed when Paul used natural versus spiritual he was not setting into opposition the physical versus an immaterial body. The two adjectives are not what something is composed of, but what it is animated by. Both our earthly and future heavenly bodies are animated by the soul/spirit.
As we try to understand the words “life-giving spirit,” verses 42-44 clearly support that the Apostle Paul did not mean Jesus rose as a spirit. Jesus eliminated that possibility when He said in Luke 24:39 “See My hands and My feet, that it is I Myself; touch Me and see, for a spirit does not have flesh and bones as you see that I have.” Jesus said He did not rise as a spirit.
What is a life-giving spirit? Paul is teaching that Jesus gives spiritual life to our mortal bodies through His Spirit who is inside us. We read in Romans 8:9-11 “However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. 10 If Christ is in you, though the body is dead because of sin, yet the spirit is alive because of righteousness. 11 But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who dwells in you.” Christ’s spirit that dwells in us is a life-giving spirit.
The spiritual life of a believer is a result of Christ living in him. Paul writes Galatians 2:20 “I have been crucified with Christ; and it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself up for me.” Galatians 4:6 “Because you are sons, God has sent forth the Spirit of His Son into our hearts, crying, “Abba! Father!” All believers have the spirit of Christ.
The Apostle Paul eliminated the possibility of a “life-giving spirit” referring to an immaterial body. In Genesis 1-2:7 God created the universe and humanity. We read in Genesis 2:7 “Then the LORD God formed man of dust from the ground, and breathed into his nostrils the breath of life; and man became a living being.” God gave life to Adam the first human. Paul then calls Jesus the last Adam and Jesus brings life to all who are born again. Jesus’ spirit gives new life to believers; hence He is a life-giving spirit. Jesus lived on earth as truly God and truly man, which explains how He can reside in heaven today in His resurrected body and as God be a life-giving spirit (see above Rom. 8:9-11).
When Paul says in verse 50 flesh and blood cannot inherit the kingdom of God, he is referring to our mortal bodies, not our immortal bodies. Flesh and blood is simply an idiom for earthly. Remember in Luke 24:39 Jesus said “See My hands and My feet, that it is I Myself; touch Me and see, for a spirit does not have flesh and bones as you see that I have.” Notice he didn’t say his body was composed of flesh and blood. The resurrected body is not a spirit but is physical and is composed of flesh and bones.
 Gundry, Robert, Soma in Biblical Theology, Cambridge University Press, 2005 p.50