References to altars appear in the Bible some four hundred times, including their construction, materials (e.g., unhewn stone, wood, earth, brass/bronze, gold), types (especially for burnt offerings in the majority of cases, with a smaller number of references to incense altars), ritual acts (especially the slaughter and burning of animal sacrifices, and the sprinkling of blood), associated fixtures and paraphernalia (e.g., staves, rings, grates, horns, and vessels used), as well as more casual aspects.
The ordinary Hebrew word for altar is mizbēaḥ, meaning “slaughtering place”; the Greek word thusiastērion has a similar meaning. In biblical and nonbiblical traditions, an altar is not a natural object but rather a built structure. It is not inhabited by a supernatural force, though it attracts that force; thus, the altar is not the same as a sacred stone.
In biblical narrative, altars are built at a location where divine‐human contact has been, or presumably could be, encountered. They are not habitation places; rather, they provide cultic access to the deity. They may be overturned, displaced, or rebuilt without any impact upon their use or meaning. Profaning them does not, therefore, affect the deity; instead, it precludes their use for proper ritual access, at least temporarily.
The altar in the Bible is a constructed platform, initially intended for slaughtering sacrifices for the God of Israel next to or upon its surface, who would visit the site regardless of its location (see Exod. 20.24). An altar, then, could be located anywhere needful or appropriate, and its installation and purpose would be accepted by the deity. Thus, the early proliferation of such installations posed no theological problem. It was only when, due to sociopolitical necessity, the cult was centralized at the Temple in Jerusalem and exclusive access to the deity was located there, that, theoretically at least, other altars were no longer permitted.
Other aspects of altars were similarly rather loosely conceived. How an altar was to be constructed—its materials, its permanency of location, and even its precise use—seem not to have been uniformly fixed. In all probability, the occasional demand for simplicity (e.g., unhewn stone for construction) can be explained only on the basis of real or fictive practice acquiring the weight of tradition, and therefore becoming proper, or on the basis of anachronistic insistence on purity.
The variation in types of altars, and the precise ritual involved for each, is perfectly explicable on both developmental and institutional grounds, as the cult developed in sophistication. However, the generic altar continued to be a point of access to the deity, regardless of the specific sacrifice made upon it to attract divine attention.
Other uses of the altar, such as a place of sanctuary or asylum place (see 1 Kings 1.50–53; 2.28–34), or for the declaration of binding oaths (Josh. 22.26–28, 34), are secondary. Since the deity could be met at altars, divine protection or divine witness could be sought at the same location.
Certain altars, especially those constructed or repaired by important people, are specifically mentioned in the Bible, either to enhance the concept, or because of the prominence of their builders. The idea of altar construction is thus carried back to Noah (Gen. 8.20), with subsequent reinforcement of the tradition attributed to Abraham and others of the ancestral family. Several kings, likewise, are singled out for having performed the same pious act: Saul, David, Solomon, and other monarchs are specifically noted.
Just as construction and use varied through time, the correct rituals for offering sacrifices varied. Various references deal with sprinkling or pouring the blood of slaughtered animals upon the altar, upon its “horns” or sides, and to burning the entire sacrifice or only the fat upon it. Uniformity developed principally with the centralization of the cult, and was read back into the time of Moses and Aaron in order to authenticate the practice.
The appearance of altars is complicated by references to “horns” (e.g., Exod. 29.12; 1 Kings 1.50; Amos 3.14). When these appurtenances first appear is difficult to judge, as is their precise use. On the basis of archaeological finds from somewhat later periods, these corner uprights may have served to support vessels containing the sacrifices, beneath which the coals of the altar were placed on grates. Such a utilitarian construction would have facilitated cleaning, as well as the actual placement of various kinds of offerings on separate occasions. This view is supported to some extent by references to the vessels of the altars as separate items.
Philip C. Hammond