Our Torah reading before Passover (Acharei Mot) concerned the yearly Yom Kippur ritual that purged the sins of the people and restored the Sanctuary to a state of purity (tahora). This week's Torah portion continues the theme of purity and begins with the LORD saying to the Israelites, "You must be holy because I, the LORD your God, am holy." The portion then proceeds to list more commandments regarding practical ethics than any other portion of the Torah, thereby directly connecting holiness with obedience to God's moral truth.
After stating the foundational requirement to be holy, the LORD begins to explain, "Each of you must respect his mother and his father, and you must keep my Sabbaths. I am the LORD your God." The duty to revere (or honor) one's parents recalls the Fifth Commandment, which is the starting point of learning to respect other people in our lives. Notice that the word for "my Sabbaths" implies both the keeping of the weekly Sabbath as well as the "appointed times" of the LORD. Sanctifying time is a way we can express practical holiness and turn away from idolatry.
The Israelites were to practice mercy by providing for the poor and the stranger by leaving the edges of the fields unharvested (pe'ah) and leaving any pieces that remain during the harvest for the poor to gather as food (leket). They also were to leave fallen fruits from their orchards for the needy to eat. The Ten Commandments were then restated, and the people were further instructed not to insult the deaf or put a stumbling block before the blind. They were to use a "good eye" when judging others and not to bear any grudges. Indeed, the essence of holiness may be stated as "You shall love your neighbor as yourself." God further instructs the people to love the stranger in their midst "kamocha" - as they love themselves, for the Jews were strangers in the land of Egypt.
Various other laws are given, including laws against various occult practices, including divination, eating blood, defiling or disfiguring the body, engaging in prostitution, and the heinous practice of child sacrifice. Sexual immorality is prohibited and punishments for sexual sins are defined. The people are warned to keep all these laws or to face being "vomited out" of the Promised Land. The portion ends: "You shall be holy to me, for I the LORD am holy and have separated you from the peoples, that you should be Mine."