In today’s terminology, “holiness” has become an ethical category. Those who act “holier than thou,” for instance, behave as though they are morally superior to others. Yet, this understanding of holiness in terms of morality is a modern shift from the ancient Hebrew definition. Rather than expressing ethics, the biblical meaning of “holy” (קדושׁ; qadosh) is set apart or separated. Related concepts like “clean” (טהור; tahor) and “unclean” (טמא; tame) have also undergone a modern moralization, but these ideas have more to do with separation than with either sin or salvation. In using these sorts of terms, the authors of Israel’s Scriptures specified the contours of cleanliness and contamination that allowed for the closest possible bond between God and humanity.
In the middle of the Torah, God tells the Israelites through Moses, “You shall be holy (קדושׁים; qedoshim), for I the Lord your God am holy (קדושׁ; qadosh)” (Leviticus 19:2). What does this phrase mean? The command can hardly mean that Israel must be as morally upright or righteous as God in heaven. Shortly before this divine declaration, the Lord establishes the sacrificial system to make atonement for “all the iniquities of the children of Israel” (16:21). God offers Israel a divine safety-net because Heaven knows that humanity will tend to transgress the commandments. Therefore, to be “holy” does not mean to be perfect or sinless like God. Instead, “holy” means “separate” from others: Israel was to be “set apart” from the nations around them.
The words that follow God’s call to holiness are instructive for understanding how the notion of “separation” functioned in ancient Israel. Moses is told to inform the people, “You shall keep my Sabbaths: I am the Lord your God. Do not turn to idols or make for yourselves and gods of cast metal: I am the Lord your God” (Lev 19:3-4). The nations other than Israel did not keep Sabbath, and they fashioned metal idols to represent their various gods in worship. Therefore, observing the Sabbath and refraining from idol-making would help to set apart Israel from their national neighbors; they would be a holy people to the Lord their God—and to that God alone. Indeed, the invocation of Sabbath is itself a nod to holiness since “God blessed the seventh day and made it holy (קדושׁ)” at creation (Genesis 2:3) — that is, “separate” from the other six days of the week.
Understanding the separateness of Israel’s God can also help to clarify what the Bible means by “holy.” When God commands Israel to be holy because “I the Lord your God am holy” (Lev 19:2) this assertion underscores the fact that the God of Israel was “set apart” from the gods of other nations. At the outset of the so-called Ten Commandments — actually, in Hebrew they’re called the “Ten Words” (עשרת הדברים; aseret hadevarim; cf. Exodus 34:28; Deuteronomy 4:13; 10:4) – God commands Israel, “You shall have no other gods (אלהים; elohim) besides me” (Exodus 20:3; cf. Deuteronomy 5:7). Literally, the Hebrew says that the Israelites should have no other gods before my face (על-פני; al-panai),” meaning that God’s people should not worship any other deities alongside their own. While many modern readers have understood these words to mean that no other gods exist apart from the God of Israel, the verse asserts the exact opposite: precisely because other options for worship exist, God commands Israel to keep their eyes only on the Lord’s face. Israel’s God was “holy” or “set apart” from other gods; thus, the Lord’s chosen people were to be “holy” just like their God.
Yet, Israel’s collective holiness does not denote any inherent righteousness or ethical superiority, despite modern misunderstandings to the contrary. Soon after Deuteronomy describes Israel as “a people holy (קדושׁ) to the Lord” (7:6), the very same book details the people’s lack of moral preeminence among their peers. Moses tells his people, “Do not say to yourselves… ‘It is because of my righteousness (צדקה; tsedakah) that the Lord has brought me in to possess this land.’ Rather, it is because of the wickedness of these [other] nations that the Lord is driving them out before you, not because of your righteousness or the uprightness (ישׁר; yosher) of your heart” (9:4-5). Thus, the original Hebrew meaning of “holy” has little to do with the kind of “holier than thou” attitude the word conjures in contemporary conversation.
A similar point holds for the Hebrew references to being clean (טהור; tahor) or unclean (טמא; tame). In the Torah, the state of being “unclean” described ritual impurity rather than moral transgression. For instance, Leviticus advises that if a person develops a skin ailment in ancient Israel “the priest shall pronounce him unclean (טמא)” (Lev 13:11). This status of uncleanness does not denote any impropriety on the part of the patient. Instead, to be unclean in this context means to be ritually impure. However, such cultic contamination was not the end of the world; once an afflicted person recovered and underwent priestly inspection, one could simply “wash his clothes, and be clean (טהר; taher)” (Lev 13:6). Thus, cleanliness was a return to a state of external purity, not an internal eradication of sin. Leviticus itself clarifies this definitional difference when it describes the oil for the tabernacle’s lamps being “pure” (טהורה; tehorah) — the same word for the “clean” person free from skin problems.
The categories of “clean” and “unclean” appear in tandem with “holiness” in the Torah. God tells Aaron the priest, “You are to distinguish between the holy (קדושׁ) and the common (חל; hol), and between the unclean (טמא) and the clean (טהור)” (Lev 10:10). The parallel Hebrew terms in this verse suggest that “holy” is conceptually similar to “clean.” Neither of these terms denotes behavioral decency or ethical advantage. Instead, what is “clean” is kept separate from what is ritually “unclean,” just as what is “holy” is set apart from the “common.” The biblical meaning of “holy” was very different from the way it functions in popular parlance. In the original Hebrew, holiness is a defining element of the divine-human relationship that sets one’s life apart for God.