Altars were places of sacrifice and worship constructed of various materials. They could be either temporary or permanent. Some altars were in the open air; others were set apart in a holy place. They could symbolize either God’s presense and protection or false worship that would lead to God’s judgment.

Old Testament

Noah and the patriarchs. The first reference in the Bible is to an altar built by Noah after the flood (Gen. 8:20). This action suggests the sanctuary character of the mountain on which the ark landed, so that theologically the ark’s resting place was a (partial) return to Eden. The purpose of the extra clean animals loaded onto the ark was revealed (cf. 7:2–3). They were offered up as “burnt offerings,” symbolizing self-dedication to God at this point of new beginning for the human race.

Abram built altars “to the Lord” at places where God appeared and spoke to him (Gen. 12:7) and where he encamped (12:8; 13:3–4, 18). No sacrifice is explicitly mentioned in association with these altars. Thus, they may have had the character of monuments or memorials of significant events. In association with Abram’s altars, he is said to have “called on the name of the Lord” (12:8)—that is, to pray. The elaborate cultic procedures associated with later Israelite altars (e.g., the mediation of priests) were absent in the patriarchal period. Succeeding generations followed the same practices: Isaac (26:25) and Jacob (33:20; 34:1, 3, 7). God’s test of Abraham involved the demand that he sacrifice his son Isaac as a burnt offering. In obedience, Abraham built an altar for this purpose, but through God’s intervention a reprieve was granted, and a ram was substituted (22:9, 13). Moses erected an altar after the defeat of Amalek at Rephidim, to commemorate this God-given victory (Exod. 17:15–16).

Moses and the tabernacle. In the context of making the covenant with Israel at Sinai, God gave Moses instructions on how to construct an altar (Exod. 20:24–26; cf. Josh. 8:31). It could be “an altar of earth” (of sun-dried mud-brick construction?) or else made of loose natural stones. The Israelites were expressly forbidden to use hewn stones, perhaps for fear of an idolatrous image being carved (making this prohibition an application of Exod. 20:4; cf. Deut. 27:5–6). Even if the altar was large, it was not to be supplied with steps for the priest to ascend, lest his nakedness be shown to God. The requirement that priests wear undergarments reflects the same concern (Exod. 28:42–43). An altar made of twelve stones, the number representing the number of the tribes of Israel, was built by Moses for the covenant-making ceremony (Exod. 24:4), in which half the blood of the sacrifice was sprinkled on the altar (representing God?) and the other half on the people, the action symbolizing the covenant bond created (24:6–8).

For the tabernacle, a portable “altar of burnt offering” was made (Exod. 27:1–8; 38:1–7). It had wooden frames sheathed in bronze and featured a horn at each corner. There was a ledge around the altar halfway up its sides, from which was hung bronze grating, and it had four bronze rings into which poles were slipped for transport. As part of the cultic ritual, blood was smeared on the horns (29:12). This altar stood in the open air in the courtyard of the tabernacle, near the entrance to the tabernacle. Included among the tabernacle furnishings was a smaller “altar of incense,” with molding around the top rim (30:1–10; 37:25–28). This altar was, however, overlaid with gold, for it stood closer to God’s ritual presence, inside the tabernacle, “in front of the curtain that shields the Ark of the Covenant law,” the curtain that separated the most holy place from the holy place. The high priest placed fragrant incense on this altar every morning and evening. The fact that this was a daily procedure and the description of the positioning of the tabernacle furnishings in Exod. 40:26–28 (mentioning the altar of incense after speaking about the lampstand) might be taken as implying that the incense altar was in the holy place, but 1 Kings 6:22 and Heb. 9:4 suggest that it was actually in the most holy place, near the ark.

God, through Moses, instructed the people that on entering the Promised Land they were to destroy all Canaanite altars along with the other paraphernalia of their pagan worship (Deut. 7:5; 12:3). Bronze Age altars discovered at Megiddo include horned limestone incense altars and a large circular altar mounted by a flight of steps. In Josh. 22 the crisis caused by the building of “an imposing altar” by the Transjordanian tribes was averted when these tribes explained to the rest of the Israelites that it was intended as a replica of the altar outside the tabernacle and not for the offering of sacrifices. The worship of all Israel at the one sanctuary both expressed and protected the religious unity and purity of the nation at this vital early stage of occupation of the land. In later narratives, however, Gideon (Judg. 6), Samuel (1 Sam. 7:17), Saul (1 Sam. 14:35), and David (2 Sam. 24) are said to build altars for sacrifice and to have done so with impunity, and in fact with the apparent approval of the biblical author. The established custom of seeking sanctuary from threat of death in the nation’s shrine is reflected in 1 Kings 1:50–53; 2:28–35, where Adonijah and Joab are described as “clinging to the horns of the altar.”

Solomon’s temple and rival worship centers. In the temple built by Solomon, the altar of incense that belonged to the “inner sanctuary” was overlaid with gold (1 Kings 6:20, 22). Solomon’s prayer at the dedication of the temple was made before the bronze altar in the courtyard (1 Kings 8:22, 54). The altar for sacrifices was much larger than the one that had been in the tabernacle (1 Chron. 4:1 gives its dimensions).

Although many of the psalms may originally have been used in worship in the first temple, there are surprisingly few references to the altar in the Psalter (only Pss. 26:6; 43:4; 51:19; 84:3; 118:27). They express the psalmist’s devotion to God and the temple as the place where God’s presence is enjoyed as the highest blessing.

After the division of the kingdom, Jeroboam offered sacrifices at the rival altar that he set up in Bethel (1 Kings 12:32–33). An unnamed “man of God” (= prophet) predicted Josiah’s desecration of this altar, which lay many years in the future (1 Kings 13:1–5). Amos and Hosea, who prophesied in the northern kingdom of the eighth century BC, condemned this and the other altars in that kingdom (e.g., Amos 3:14; Hos. 8:11–13). Ahab set up an altar to Baal in Samaria (1 Kings 16:32), and the suppression of Yahwism by Jezebel included the throwing down of the Lord’s altars in Israel (19:10, 14). The competition on Mount Carmel between Elijah and the prophets of Baal involved rival altars (1 Kings 18), and Elijah’s twelve-stone altar recalls that of Exod. 24, for he was calling the nation back to the exclusive monotheism preached by Moses (1 Kings 18:30–32).

With regard to the southern kingdom, the spiritual declension in the time of Ahaz manifested itself in this king making an altar modeled on the Assyrian prototype that he had seen on a visit to Damascus (2 Kings 16:10–14). He shifted the Lord’s altar from in front of the temple, where it had previously stood. Godly Hezekiah’s religious reform included the removal of the altars at the high places that up to that time had been centers of deviant worship (2 Kings 18:4, 22). The apostasy of King Manasseh showed itself in his rebuilding the high places that Hezekiah his father had destroyed and in erecting altars to Baal (2 Kings 21), thus repeating the sin of Ahab (cf. 1 Kings 16:32). Josiah’s reform included the destruction of all altars outside Jerusalem (2 Kings 23) and the centralizing of worship in the Jerusalem temple.

In Ezekiel’s vision of the new temple of the future, the sacrificial altar is its centerpiece (Ezek. 43:13–17). The altar was to be a large structure, with three-stepped stages and a horn on each corner, and it was to be fitted with steps on its eastern side for the use of the priests.

The second temple. The Israelites’ return from Babylonian exile was with the express aim of rebuilding the temple. The first thing that the priests did was to build “the altar on its foundation” (i.e., its original base; Ezra 3:2–3). The returnees placed the altar on the precise spot that it had occupied before the Babylonians destroyed it along with the temple. They took such care because they wanted to ensure that God would accept their sacrifices and so grant them protection. At the very end of the OT period, the prophet Malachi condemned the insincerity of Israel’s worship that was manifested in substandard sacrifices being offered on God’s altar (Mal. 1:7, 10; 2:13).

New Testament

In the NT, the altar is mentioned in a number of Jesus’ sayings (e.g., Matt. 5:23–24; 23:18–20). In the theology of the book of Hebrews, which teaches about the priesthood of Jesus Christ (in the order of Melchizedek), the role of the priest is defined as one who “serve[s] at the altar” (7:13), and Christ’s altar (and that of Christ’s followers) is the cross on which he offered himself as a sacrifice for sin (13:10). Another argument of Hebrews is that since on the most important day in the Jewish ritual calendar (the Day of Atonement), the flesh of the sacrifice was not eaten (see Lev. 16:27), the eating of Jewish ceremonial foods is not required, nor is it of any spiritual value. The altar in the heavenly sanctuary is mentioned a number of times in the book of Revelation (6:9; 8:3, 5; 9:13; 11:1; 14:18; 16:7). It is most likely the altar of incense and is related to the prayers of God’s persecuted people, which are answered by the judgments of God upon the people of the earth.