King James Bible
"But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his."
Paul contrasts two modes of existence: 'in the flesh' (dominated by sinful nature) versus 'in the Spirit' (controlled by God's Spirit). This marks a fundamental transformation for believers, shifting from the old self-centered life to a new Spirit-directed existence. The indwelling of God's Spirit serves as the condition and evidence of this new life. Paul uses 'if' not to express doubt but to establish the defining characteristic of true Christians—the Holy Spirit permanently residing within them. Paul makes an absolute statement: possessing Christ's Spirit is non-negotiable for belonging to Christ. The interchangeable use of 'Spirit of God' and 'Spirit of Christ' affirms the deity of Christ while establishing that genuine Christianity requires supernatural transformation, not mere profession.