Our bodies are temples of God.

In "Achieving a Celestial Marriage" student manual it states:

"Two exciting elements of mortality, both God-given, are worthy of our consideration. The first is that we receive a body that is physical, tangible, one that has feelings and powers not enjoyed by a spirit. This body is to facilitate our progress toward becoming like our Heavenly Father. Keep in mind the truth that this 'gift' was created in the exact likeness of Him whose children we are. The second element is that some powers given to us through our bodies are inherently of God, and are unique to his order of life. Our natural feelings concerning the power to reproduce 'after our own kind' are holy and desirable. All we have and are, so far as our natural state is concerned, is good, for it is of God (Alma 5:40)...The powers to reproduce, then, are good, and cannot be considered evil. Only when wicked men misuse this sacred gift can it properly be called evil, for in the holy state of marriage these powers are expressed in sacred propriety"