We recognize the true seriousness of sin when we realize that all sin is committed against God. But another serious effect is that it is committed against oneself (Habakkuk 2:9-10; I Corinthians 6:18). Our bodies are not our own; Jesus bought us with His own blood. So we must glorify God in our body and in our spirit, which are His (I Corinthians 6:19-20).
