The Altar, from a word meaning "place of slaughter," in the period of the patriarchy was the center of personal and family worship, being the place of sacrifice and surrender to God.
Mizbēaḥ: A masculine noun meaning the altar, the place of sacrifice, is a noun formed from the verb zāḇaḥ, which means to slaughter an animal, usually for a sacrifice. The sacrificial system was at the central point of the pre-Israelite and Israelite systems of worship since the sacrifice and following meal were used to solemnize a covenant or treaty and to symbolize an unbreakable relationship between the two parties.
In a short but interesting essay on the Jewish altar by David Mill, it is noticed that the Rabbinical writers used to regard it not only as God's table' (see Mal. 1. 7), but also as a symbol of mediation; accordingly, they called it a, Paraclete i.e. an intercessor; it was regarded as a centre for mediation, peace-making, expiation, and sanctification. Whatever was burnt upon the altar was considered to be consumed by God and guarantee that the offerer was accepted by Him.
Noah built an altar and offered sacrifices on exiting the ark (Gen 8:20); the patriarchs built altars and sacrificed at various points along their journeys: Abram (Gen 12:7-8; Gen 22:9); Isaac (Gen 26:25); Jacob (Gen 35:7); Moses (Exo 24:4). At Mount Sinai, God commanded that the Israelites build the Tabernacle and include two altars: a bronze altar in the courtyard for the sacrificing of animals (Exo 27:1-8; Exo 38:1-7) and a golden altar inside the Tabernacle for the burning of incense (Exo 30:1-10; Exo 37:25-29). Solomon (1Ki 6:20, 1Ki 6:22; 1Ki 8:64) and Ezekiel (Eze 41:22; Eze 43:13-17) followed a similar pattern. God also commanded that the altar for burnt offerings be made of earth or undressed, uncut stones because human working of the stones would defile it. Moreover, God commanded that the altar should have no steps so that human nakedness would not be exposed on it (Exo 20:24-26).
As Enoch did, so did those that built an altar to the Lord, they "called upon the name of the Lord". In the New Testament to "call upon the name of the Lord" signifies complying with his directions as to worship and obedience (Rom. 10:13; Acts 9:4; 22:16). So also, Abraham at Beersheba is said to have "called on the name of the Lord, the Everlasting God" (Gen. 21:33); in view of his previous practice of altar building.
In addition, when Abraham built an altar in the land was, in fact, a form of taking possession of the promised land. The worship of God in the new land expressed Abraham's faith in the fulfilment of the divine promise. Abraham was already in the land of promise, and could leave the future conquest of the promise to God. Thus, Abraham was, by building those altars, taking possession of the land. The building of altars by Abraham and his purchase of the field of Machpelah was an indirect way of possessing the land for God. The places Abraham visited and built altars of sacrifice and worship were the same places the armies of Israel fought and conquered when they entered the land of Canaan. After the fall of Jericho, the first city the Israelites conquered was Ai, the location of which is expressed with the same words used in Genesis 12:8: "With Bethel on the west and Ai on the east" (see Joshua 7:2; 8:9, 8:12). After the conquest of Ai, the Israelites built an altar to the Lord on Mount Ebal, an area near Shechem (Joshua 8:30).Thus, the conquest of the land of Canaan had already begun when Abraham built those altars and when he bought the land of Machpelah. The same applies to the believer that when we surrender at the altar in obedience to God's geographic will and his perfect will, we possess the land by faith.
That Abraham was a man of great faith there is no doubt. Scripture so attests (Heb. 11:8-10, 17; Rom. 4). Let's look at Abraham's 5 altars.
1. The Altar of Promise - obedience (Genesis 12:5-7)
Stephen recounts it thusly: "Men and brethren and fathers, listen: The God of glory appeared to our father Abraham when he was in Mesopotamia, before he dwelt in Haran, and said to him, `Get out of your country and from your relatives, and come to a land that I will show you.' Then he came out of the land of the Chaldeans and dwelt in Haran. And from there, when his father was dead, He moved him to this land in which you now dwell" (Acts 7:2-4). When Abram arrived in Canaan at Sichem, after the Lord again appeared to him saying, "To your descendants I will give this land"; and of Abraham it is related, "And there he built an altar to the Lord, who had appeared to him"
2. The Altar of Intimacy - prayer (Genesis 12:8)
Then upon moving south to near Bethel he again "built an altar to the Lord and called on the name of the Lord"
3. The Altar of Returning - returning and repentance (Genesis 13:3-4)
After his backsliding in Egypt, necessitated by the famine in Canaan, he came back to the altar site near Bethel, "And there Abram called on the name of the Lord"
4. The Altar of Possession - walk of faith (Genesis 13:17-18)
Further, when he and Lot had separated and Abram moved to the region of Hebron by faith, he "built an altar there to the Lord"
5. The Altar of Absolute Surrender and Trust - sacrifice and worship (Genesis 22:9)
While he was still in the land of the Philistines, God tested him, telling him to go to Moriah and offer Isaac for a burnt offering. Upon their arrival, "Abraham built an altar there"
When we go back and look at Abraham's journey and his altar building following significant events in his life, we notice two times when no reference is made to his having built an altar after a major change in conditions. When he went to Egypt, nothing is said of his building an altar there; and that is the first time he lied regarding Sarah. When he went to Gerar in the region of Kadesh and Shur, nothing is said of his building an altar. And he again he practiced deception when Abimelech, king of Gerar "sent and took Sarah" (Gen. 20:2). It was only after this incident and one involving a well of water which Abimelech's servants had taken from Abraham's herdsmen that the record tells us that "Abraham planted a tamarisk tree in Beersheba, and there called on the name of the Lord, the Everlasting God" (Gen. 21:33). After the encounter with Pharaoh, Abraham was expelled from Egypt. They "sent him away, with his wife and all that he had" (Gen. 12:20). He returned to the place of his altar between Bethel and Ai (Gen. 13:3-4). It was after his successfully making a treaty with Abimelech that in Beersheba he "called on the name of the Lord, the Everlasting God" (21:33).
Building an altar and sacrificing all of ourselves to God denotes total dependence and reliance on Him. It implies saying no to self and yes to God—in effect presenting one's self in submission to God as a sinner, trusting Him in grace, and discounting our value apart from His work - Rom 12:1,2. Building altars became a habit with godly Abraham, the "Friend of God" (James 2:23) and so we may also in our faith journey with Christ in this world.