There is probably no religion without a distinction between holy and profane, and in most, if not indeed at all, the religious man is the one to whom something is holy.
The principle biblical words are qadosh and qodesh in the Tanakh (Old Testament) and hagios in the Messianic Scriptures (New Testament), all words of uncertain derivation. If the Semitic origin of qadosh be accepted, it may come from a root expressing 'separation' or 'cutting off', applied to the separation of a person or thing to divine use, and so eventually to the state of the object or person so reserved.
Hagios in the Messianic Scriptures (New Testament) is the nearest equivalent to the Hebrew qadosh (probably from the same source as hagnos signifying 'pure') and has the same fundamental thought of separation and so of consecration to Elohim (God). Hosios is also as the equivalent of the Hebrew chasid and, like it, implies the right relationship to Elohim (God) as holy or pious, with the further connotation, perhaps, 'beloved of' Elohim (God). In this latter sense the Messiah is termed "the Qadosh (Holy) One" (Ac.2:27). It may not have, in the first instance, the same ethical implications as hagios, though in Titus 1:8 it certainly connotes holy character.
In the Tanakh (Old Testament), holiness is designated of places, things, seasons, and official persons, in virtue of their connection with the worship of Yahweh. The first application of the term is to the sabbath which Yahweh made qadosh (holy) (Gen.2:3). It is likewise applied to the place of worship or sanctuary used in the worship of Elohim (God). Similarly, it is used in connection with persons, cohenim (priests), Levites, etc. officially connected with the worship of Yahweh. In these instances, holiness signifies a relation that involved separation from common use and dedication to a sacred one.
A. The Holiness of Elohim's Character
Holiness in the Tanakh (Old Testament), as in the Messianic Scriptures (New Testament), is applied in the highest sense to Elohim (God). It denotes, first, His separation from the creation and elevation above it. It thus sets forth the transcendance of Elohim (God). Yahweh as the Qadosh (Holy) One stands in contrast to false gods (Ex.15:11) and to the whole of creation (Is.40:25).
The word also denotes relationship, and signifies Yahweh's determination to preserve His own position relative to all other free beings. It is Elohim's (God's) self-affirmation, "the attribute in virtue of which Yahweh makes Himself the absolute standard of Himself" (Godet). Not only does it bring out the contrast between the divine and the human (Hos.11:9), but it becomes almost synonymous with supreme deity, and emphasises, in particular, the awe-inspiring side of the divine character (Ps.99:3).
The ethical quality in holiness is, however, the aspect under which the term is most commonly applied to Elohim (God). Holiness is a term for the moral excellence of Elohim (God) and His freedom from all limitations in His moral perfection (Hab.1:13). In this exalted sense Elohim (God) only is qadosh (holy) and so the standard of ethical purity in His creatures (people and malakim/angels).
Since holiness embraces every distinctive attribute of Elohimhead (Godhead), it may be defined as the outshining of all that Elohim (God) is. As the sun's rays, combining all the colours of the spectrum, come together in the sun's shining and blend into light, so in His self-manifestation all the attributes of Elohim (God) come together and blend into holiness. Holiness has, for that reason, been called 'an attribute of attributes', that which lends echadness or unity to all the attributes of Elohim (God). To conceive of Elohim's (God's) being and character as merely a synthesis of abstract perfections is to deprive Elohim (God) of all reality. In the Elohim (God) of the Bible these perfections live and function in holiness.
For these reasons we can understand why holiness is expressly attributed in Scripture to each Person of the Elohimhead (Godhead), to the Father, Yahweh (Jn.17:11), to the Son, Yah'shua (Jesus) (Ac.4:30) and especially to the Ruach haQodesh (Holy Spirit) who manifests and communicates the holiness of Elohim (God) to His creatures.
B. The Holiness of Elohim in Relation to His People
The Tanakh (Old Testament) applies the word 'qadosh (holy)' to human beings in virtue of their consecration to spiritual purposes, e.g. cohenim (priests) who were consecrated by special ceremonies, and even to the whole nation of Israel as a people separated from the nations and consecrated to Yahweh. Thus it was relationship to Elohim (God) that constituted Israel a qadosh (holy) people, and in this sense it was the highest expression of the covenant relationship. This idea is present in the Messianic Scriptures (New Testament) too as in the passage in 1 Corinthians 7:14, where the unbelieving husband is sanctified in virtue of his relationship to the believing wife and vice versa, though in this case only for as long as the believing partner is alive.
But as the conception of holiness advanced, alongside the progressive revelation of Elohim (God), from the outside to the inside, from ceremonial to reality, so it took on a strong ethical significance, and this is its main, and practically exclusive, connotation in the Messianic Scriptures (New Testament). The Tanakh (old Testament) nevi'im (prophets) proclaimed it as preeminently Elohim's (God's) self-disclosure, the testimony He bears to Himself, and the aspect under which He wills His creatures to know Him. Moreover, the nevi'im (prophets) declared that Elohim (God) willed to communicate His holiness to His creatures, and that, in turn, He claims holiness from them. If "I (Yahweh) am qadosh (holy)" (Lev.11:14) is the divine self-assertion, lifting Elohim (God) immeasurably above His creatures, so "be qadosh (holy)" (Lev.20:7, NKJV; cp. 1 Pet.1:15-16) is the divine call to His creatures to "share in (be partakers of) His holiness" (Heb.12:10, NIV). It is this divine imparting of the divine holiness which takes place in the soul of man in regeneration and becomes the spring and foundation of qadosh (holy) character.
Messiah in His life and character is the supreme example of the divine holiness. In Him it consisted in more than mere sinlessness: it was His entire consecration to the will and purpose of Elohim (God), and to this end Yah'shua (Jesus) sanctified Himself (Jn.17:19). The holiness of Messiah is both the standard of the Christian/Messianic character and its guarantee:
In the Messianic Scriptures (New Testament) the apostolic designation for Christians/Messianics is qodeshim (saints, set-apart or holy ones), and it continued to be used as a general designation at least up to the days of Irenaeus and Tertullian, though after that it degenerated in ecclesiatical usage into a honorific title. Though its primary significance was relationship, it was aslo descriptive of character, and more especially to Messiah-like character. In is in this sense that the word is used by Messianic Evangelicals.
"Both the One who makes men qadosh (holy) and those who are made qadosh (holy) are of the same family" (Heb.2:11, NIV).
The Messianic Scriptures everywhere emphasises the ethical nature of holiness in contrast to all uncleanness, i.e. the unkosher nature, both unmanifested (in the thoughts and feelings) and manifested (in behaviour). It is represented as the supreme vocation of true believers and the goal of their living. In the final assessment of human destiny, the two categories known to Scripture are the righteous and the wicked.
C. The Eschatological Significance of Holiness
Scripture emphasises the permanence of moral character (Rev.22:11). It also emphasises the retributive aspect of the divine holiness. It involves the world in judgment. From a moral necessity in Yahweh-Elohim, life is so ordered that in holiness is welfare, in sin is doom. Since the divine holiness could not make a universe in which sin would ultimately prosper, the retributive quality in the divine government becomes perfectly plain. But retribution is not the end (see Hell) - the holiness of Elohim (God) ensures that there will be a final restoration, a palingenesia, bringing to pass a regeneration of the moral universe. The eschatology (concerning the final events of history or 'end times') of the Bible holds out the promise that the holiness of Elohim (God) will sweep the universe clean, and create new heavens and a new earth in which righteousness will dwell undisturbed (2 Pet.3:13).