Leviticus 4:1–35 relates the Lord’s commands concerning a sin offering. Sin, of course, formed a barrier preventing any contact with the Lord God (because of sin God drove Adam and Eve out of Paradise; see Genesis 3:23–24). An animal was killed on the bronze altar in the place of the sinner dying for his own sins (thus foreshadowing the coming work of Jesus Christ). The Lord instructed that the priest should capture some of the blood from the animal offered as a sin offering, bring it inside the tabernacle, and daub it on the horns of the altar of incense that stood “before God” (Leviticus 4:7). The point of the ritual was to teach the people the blessed consequence of the forgiveness of sins: the way is open again for sinners to speak to God in prayer (see Romans 5:1–2). So we are to understand the four horns of the altar John sees in heaven as (metaphorically) touched with the blood of the Saviour’s finished work on the cross.
13 Then the sixth angel blew his trumpet, and I heard a voice from the four horns of the golden altar before God,