Catholic Commentary
Purification of the Altar
18“He shall go out to the altar that is before Yahweh and make atonement for it, and shall take some of the bull’s blood, and some of the goat’s blood, and put it around on the horns of the altar.19He shall sprinkle some of the blood on it with his finger seven times, and cleanse it, and make it holy from the uncleanness of the children of Israel.
Leviticus 16:18–19 describes the high priest applying mingled blood from both the bull and goat sacrifices to the horns of the outer altar, then sprinkling it seven times to cleanse and consecrate the altar from the accumulated uncleanness of Israel. This ritual reverses the annual accumulation of sin-defilement that has penetrated the sanctuary through the people's imperfect offerings.
Even the altar of God absorbs the year's accumulated sin and requires blood to be made holy again—a pattern that culminates in Christ's one perfect sacrifice applied through sacraments across time.
Leviticus 16:18 — Going Out to the Altar
The movement in verse 18 is theologically deliberate. The high priest has already performed rites within the Holy of Holies (vv. 14–15) and at the incense altar (v. 16); now he "goes out" to the altar of burnt offering that stands in the outer court, before the sanctuary entrance. The phrase "before Yahweh" (לִפְנֵי יְהוָה) insists that even this exterior station is within the divine presence — there is no neutral or merely secular space in the sanctuary complex.
The priest takes blood from both the bull (sacrificed for the priesthood, v. 11) and the goat (sacrificed for the people, v. 15) and mingles them. This dual blood is significant: priest and people are implicated together in the defilement that has accumulated on the altar. The blood is applied to "the horns of the altar" — the four projecting corners at each upper edge. The horns were the altar's most sacred points, the place to which a person in flight might cling for sanctuary (1 Kgs 1:50), and the locus of other major sacrificial applications (Exod 29:12; Lev 4:7). To anoint all four horns is to encompass the totality of the altar's ritual surface, leaving no corner unaddressed.
Leviticus 16:19 — Seven-fold Sprinkling and the Making Holy
Verse 19 specifies a seven-fold sprinkling — seven being the number of completeness and of covenant in Israel's symbolic world (cf. seven days of creation; seven-branched menorah). The sprinkling is not merely hygienic; it is re-creative. The verb sequence is triadic and climactic: sprinkle — cleanse — make holy (וְטִהֲרוֹ וְקִדְּשׁוֹ). This movement from defilement through purification to consecration mirrors the logic of Israel's entire sacrificial economy. The altar is not simply washed; it is made holy from the uncleanness of the children of Israel — meaning the altar had absorbed, in some cultic sense, the moral and ritual impurity that the people brought into God's presence through their sins over the preceding year.
The Logic of Altar Defilement
Modern readers may wonder how an inanimate object is "defiled." Jacob Milgrom's influential analysis, consonant with patristic instincts, holds that in Israel's theology, sin creates a kind of contagion that attaches to sacred space. The greater the sin, the deeper into the sanctuary it penetrates (cf. Lev 4's gradient: lay person → anointed priest → Holy of Holies). Yom Kippur reverses this annual accumulation in a single concentrated rite. The altar, as the point of contact between human offering and divine acceptance, bears the weight of Israel's worship — including its imperfect, sinful, and defective offerings.
Typological Sense
The Fathers read this rite as a figure of Christ's priestly passion. Origen (Homilies on Leviticus, IX) notes that the high priest moves from the inner sanctuary outward, just as Christ, having accomplished the inner work of his divine will, "went out" to Calvary. The mingled blood of bull and goat — priest and people — is a type of Christ who is both priest and victim, and who represents all humanity before the Father. The horns of the altar, anointed with blood, prefigure the cross itself, whose four arms reach in all directions — a cosmic altar. The seven-fold sprinkling anticipates the fullness (seven = completeness) of the Spirit's sanctifying work poured out through the blood of the New Covenant.
Catholic tradition finds in these two verses a concentrated image of Christ's high-priestly work as expounded in the Letter to the Hebrews. Hebrews 9:11–14 directly contrasts the blood of bulls and goats with the "blood of Christ, who through the eternal Spirit offered himself without blemish to God," purifying "our conscience from dead works." The altar of Leviticus 16 is not merely a stone structure; it images the whole order of worship that sin has contaminated — including the human heart itself. Christ's blood, the Catechism teaches, "atones for our sins" and "reconciles us with God" (CCC 1992), accomplishing permanently what Yom Kippur enacted annually.
St. Cyril of Alexandria (Glaphyra on Leviticus) sees the mingling of the two bloods as signifying the union of divinity and humanity in the one Person of Christ: the blood of the bull (the powerful, priestly animal) and the goat (the sin-bearing victim) together figure the one sacrifice that is both divine and human in its efficacy.
The seven-fold sprinkling has been linked by theologians such as St. Thomas Aquinas (Summa Theologiae III, q.22) to the seven sacraments through which Christ's sanctifying blood is applied to the Church across time. Just as the single Day of Atonement blood was sprinkled repeatedly and completely upon the altar, so Christ's one sacrifice (Heb 10:14) is perpetually applied through the sacramental economy. The Council of Trent (Session XXII) explicitly teaches that the Mass is not a new sacrifice but the same sacrifice of Calvary made present — the same blood, as it were, applied anew to the altar of the Church.
The triad "sprinkle — cleanse — make holy" anticipates the theology of baptismal grace: we are cleansed of original and personal sin and elevated to holiness, not by our effort, but by the application of Christ's redeeming blood (CCC 1227–1228).
The image of the altar absorbing Israel's year-long accumulation of sin is a remarkable mirror for the Catholic conscience. Every Mass, celebrated in a church whose altar is itself consecrated by sacred chrism and the relics of martyrs, is the site where the contamination of our weekly, daily failures meets the purifying blood of Christ. This passage invites Catholics to approach the altar — whether as communicants or as those who kneel before the tabernacle — not with casual familiarity but with the reverence of people who know that holy things bear the weight of human sin only because they are sustained by divine mercy.
Practically, Leviticus 16:18–19 speaks to the theology of Confession. The seven-fold sprinkling that moves from defilement to holiness is realized concretely in the sacrament of Penance, where Christ's atoning blood is applied to the individual conscience. Catholics tempted to minimize regular Confession — thinking their sins "not serious enough" — might reflect that even the altar, the holiest instrument of Israel's worship, required annual blood-purification. No sacred thing in a sinful world stands immune from contamination; and no contaminated thing is beyond the reach of the blood that the High Priest has carried into the true sanctuary once and for all (Heb 9:12).