And thou shalt make an altar of shittim wood, five cubits long, and five cubits broad; the altar shall be foursquare; and the height thereof shall be three cubits.  Hollow with boards shalt thou make it: as it was shewed thee in the mount, so shall they make it. (Ex. 27:1, 8)     

The brazen altar was the place of sacrifice and stood just inside the gate.  It typifies the Cross of Christ. There was no admission to the rest of the Tabernacle through the mediation of the priests unless one stopped first and offered the substitutionary sacrifice. 

The altar was a very simple hollow box made of shittim (acacia) wood, overlaid with brass, seven and a half feet square, standing four and a half feet high.  A brass grate extended through its middle in which brass rings were fastened at each corner; wooden staves covered with brass were put through the rings for carrying the altar.  The shittim wood speaks of Christ’s perfect humanity, the brass speaks of God’s judgment.  There was no gold in the brazen altar.  Gold typifies Deity. The brazen altar typifies judgment (brass) on man (wood,)  and more particularly it typifies God’s judgment on His own Son, Who was Perfect Man, without spot or blemish – hence the hard shittim wood of the Sinai desert. All of the furnishings of the tabernacle –  except the brazen altar and the brazen laver – were overlaid with gold, representing Deity. These two items, however, emphasize judgment upon sinful man, while the other furnishings speak of restored communion of sinful man to God. The brazen altar, in particular, sets forth God’s judgment on sinless perfection as a substitutionary sacrifice for sinful man.

Without the shedding of blood, there is no remission of sin. (Lev. 17:11; Heb. 9:22.)

The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world. – John 1:29.

 And as Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up. That whosoever believeth in him should not perish but have eternal life – John 3:14, 15.

Soberly, the Israelites brought the prescribed offerings without spot or blemish to the priests, who stood at the Tabernacle’s gate to receive them.  The offerers laid their hands on the heads of the animals, symbolic of their identification with the animal’s substitutionary death on their behalf.  The offerer’s sin was symbolically transferred to the sacrifice, and the innocence of the sacrifice was symbolically transferred to the offerer.  The offerer then killed the animal, while the priest caught the sacrificial blood in a basin to be offered as an atonement.  The priest, functioning as a mediator, sprinkled the blood of the sacrifice on the altar and poured the remaining blood in the basin at the altar’s base.  Then the priest cut the sacrifice into pieces, washed the inner parts, and burned various pieces on the altar as a sweet savor to the Lord.

And thus an innocent lamb bore the judgment of the guilty.

No further activity could take place in the Tabernacle, nor could the sinner advance any further until the sacrifice was offered and the blood sprinkled in every part of the Tabernacle.  The sinner himself could not advance in the Old Testament type.  Only the priests acting as mediators were allowed to minister beyond the brazen altar.  Today, believers are themselves priests unto God; as there is only one Mediator between God and man, the Man Christ Jesus. 

1 Peter 2:5
Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ.

1 Peter 2:9
But ye [are] a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light