Albert Barnes Commentary 1 Corinthians 6:19

"Or know ye not that your body is a temple of the Holy Spirit which is in you, which ye have from God? and ye are not your own;" — 1 Corinthians 6:19 (ASV)

What? Do you not know? etc. This is the fifth argument against this sin. The Holy Ghost dwells in us; our bodies are his temples, and they should not be defiled and polluted by sin (see Barnes' notes on 1 Corinthians 3:16–17).

As this Spirit is in us, and as it is given to us by God, we ought not to dishonor the gift and the Giver by pollution and vice.

And you are not your own. This is the sixth argument which Paul uses. We are purchased; we belong to God; we are his by redemption, by a precious price paid; and we are bound, therefore, to devote ourselves, body, soul, and spirit, as he directs, to the glory of his name, not to the gratification of the flesh (see Barnes' notes on Romans 14:7-8).