What! know ye not ... - This is the fifth argument against this sin. The Holy Spirit dwells in us; our bodies are his temples; and they should not be defiled and polluted by sin; see the note at 1 Corinthians 3:16-17. As this Spirit is in us, and as it is given us by God, we ought not to dishonor the gift and the giver by pollution and vice.
And ye 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 the note at Romans 14:7-8.