In Leviticus chapter eighteen, verse six, the Lord speaks to Moses about not uncovering the nakedness of others. “Uncover the nakedness” has general sexual connotations but does not necessarily mean consummated sex acts. It involves the entire realm of impure sexual activity and play, including doings that fall short of sexual intercourse. Therefore any sexual activity involving the uncovering of, exposing of, or looking at the nakedness of another person who is not a lawful wife or husband oversteps God’s boundaries of purity and is a severe sin against Him and His law.
God declares to Moses that “none of you” means the children of Israel and God’s people, in general, shall approach any that are relatives and non-relatives. The remaining verses in this chapter explain the details of “the rest of his flesh.” A person of the same flesh and blood as other relatives are united in the bonds of the family relationship. Therefore, a man is his mother, sister, and daughter: his mother, of whom they were born, his sister, who lay in and sprung from the same “venter” he did, and his daughter, who is his flesh; and for a woman, her father brother, and son, who are in the same degree of relation, and both sexes in this prohibition.
Now when men and women are forbidden to “approach” those of the same flesh and blood with them. The sense is not that they may not come into each other’s company, use any civil or friendly salutations, or have familiar conversation with each other, provided that the preservation of modesty and chastity are intact. However, they are not so to draw near as to lie with or have carnal knowledge of one another, in which sense to tempt it or solicit it.
Those parts, which, by a contrary way of speaking, are so called, should never be naked or exposed to view; but should always be covered, as nature teaches us to do and as our first parents did.