1Corinthians 6:17-20 But he that is joined unto the Lord is one spirit. Flee fornication. Every sin that a man does is without the body; but he that commits fornication sins against his own body. What? know you not that your body is the temple of the Holy Ghost which is in you, which you have of God, and you are not your own? For you are bought with a price: therefore glorify God in your body, and in your spirit, which are God’s.
‘But he that is joined unto the Lord is one spirit.’ This is the true doctrine of interpenetration and not persons entering physical into each other. The Bible does speak of the Corinthians and Philippians being in Paul’s heart (2Cor. 7:3; Php. 1:7); God being in Christ (2Cor. 5:19); Christ being in God (John 14:20); God and Christ being in each other (John 14:10-11); men being in both the Father and the Son (1Jn. 2:24); men being in Christ (2Cor. 5:17); men and the Spirit being in each other (Rom. 8:9); Christ being in men (Col. 1:27; Rom. 8:10); man and Christ being in each other (John 14:20); all creation being in God (Acts 17:28); and satan entering into men (Luke 22:3; John 13:27). However, these passages refer to being in union with, being consecrated to the same end – one in mind, purpose, and life. They do not teach the physical entrance of one being into another. It may be best understood by a man and woman becoming one in life together, being in each other’s plans, life, etc.
‘Every sin that a man does is without the body; but he that committed fornication sinned against his own body.’ All sins destroy, but he who commits fornication sins against his entire constitution, even his body, soul and spirit.
‘What? know you not that your body is the temple of the Holy Ghost which is in you, which you have of God, and you are not your own?’ Believers are the temple of God for the indwelling of the Holy Spirit thus we cannot do harm physically or spiritually to it through a sinful life or lose the presence and unity of the Holy Spirit (Eph 4:30; 1Thes. 5:19). People are now to bring themselves to God instead of sacrifices to the altar as of old. They are now to be wholly the Lord’s as were the former sacrifices (Rom. 12:1-2). Righteousness cannot mix with lawlessness; light can have no communion with darkness; Christ and Belial cannot be of one accord; a believer cannot have part with an infidel, and there can be no agreement of the temple of God with idols (2Cor. 6:14-7:1).
‘For you are bought with a price: therefore glorify God in your body, and in your spirit, which are God’s.’ As the slave is the sole property of his master, so we, having been bought by the precious blood of Christ, are not our own (6:19-20; 7:23; 1Pet. 1:18-23).