THE ARK OF THE COVENANT and the SEAT OF ATONEMENT

"You must make me an ark of acacia wood, [...]. There I shall come to meet you; from above the mercy-seat, from between the two winged creatures which are on the ark of the Testimony, I shall give you all my orders for the Israelites." Exodus 25:10, 22

The holiest relic of the Sinai Covenant was the Ark of the Covenant, a wooden box covered with gold and topped with a lid known as the "Seat of Atonement," the earthly throne of Yahweh. This holy chest, copied from what Moses saw in heaven, was placed in the Holy of Holies in the desert Tabernacle and later in the Temple in Jerusalem. The Ark of the Covenant served 3 purposes:

It was a receptacle to hold the 10 Commandments,
It was a support for the "Seat of Atonement" as the earthly throne of Yahweh and
It was the most holy altar of Yahweh.

As the visual reminder of the presence of God with His chosen people, the Ark of the Covenant was a receptacle which held and preserved the two tablets of the Ten Commandments [Exodus 25:16]. This purpose gave the Ark its other name, the "Ark of Testimony" or the "Ark of the Covenant", recalling the Covenant which Yahweh formed with Israel at Mount Sinai [Exodus 19-31]. The tablets are called "the tablets of the Covenant" in Deuteronomy 9:9, 11, 15; and the words engraved on them are called "the words of the Covenant" [Exodus 39:28]. The Ark would also later come to hold a pot of the manna with which Yahweh had physically sustained Israel in her desert journey and the staff of the High Priest Aaron, a branch which had miraculously come to life and blossomed [see Hebrews 9:4]. The Ark served as a support for the "Seat of Atonement" or "Mercy Seat", in Hebrew the Kapporeth [Exodus 37:1-9]. The Kapporeth was placed on the top of the Ark, enclosing the tablets of the Ten Commandments within the chest of the Ark, making the tablets a treasure entrusted to Israel. The divine testimony of God hidden in the Ark became the guarantee of the fulfillment of the promises of the Covenant made at Sinai.

But the Kapporeth was more than a lid to cover the 10 Commandments. This is evident from its name which means in Hebrew not simply "covering" but instead "seat" of atonement, which some scholars translate as "Mercy Seat". This title denotes not a physical or material covering but a spiritual covering of something. But what is "covered" can not be the tablets of the Law. After all it is not the Law that must be covered, the whole purpose of the Law was that it was to be revealed continuously as the voice and will of Yahweh, but the question of sin was a serious issue. The Kapporeth instead was meant to provide a covering for the sins of Israel, the Covenant people. Israel must come to Yahweh as the sinless Bride and therefore united with Yahweh in covenantal union she must have recourse to atonement for sins, as Yahweh sat enthroned upon the "Seat of Atonement", the highest means of atonement in the Old Covenant. And yet that atonement could only be offered for unintentional sin, the blood of an animal was not perfect enough to offer expiation for mortal or deadly sins [Numbers 15:22-31]. It was in that function of the atonement for sins that the Kapporeth was a foreshadow of the true act of expiation which would be offered in the fullness of time by Christ Jesus, the Bridegroom of His New Covenant Bride, the Universal Church, upon the "mercy seat" of the Cross when His pure and holy sacrifice would cleanse the sins of all mankind for all time in all the ages of man. In Exodus 40:34-35 the glory of Yahweh came down and overshadowed the Kapporeth in the Holy of Holies of the Tabernacle as Yahweh took His place upon His earthly throne [also see Exodus 25:22 and Numbers 7:89]. Like the angelic cherubim who surround the throne of Yahweh in the heavenly Tabernacle [Revelation 4-5], of which the earthly Tabernacle is only a copy [Exodus 25:8-9; 27:8; Numbers 8:4; Hebrews 9:23], two cherubim were placed by Yahweh's command on top of the Kapporeth and images of cherubim were also woven into the inner curtain that hung in front of the entrance to the Holy of Holies in which the Ark rested. In the Tabernacle Yahweh was enthroned between the cherubim, ready to offer mercy and forgiveness to His covenant Bride Israel.

The third purpose of the Ark of the Covenant was its use as Yahweh's holiest Altar of sacrifice. The other two altars were the bronze Altar of Burnt Offerings in the courtyard [Exodus 27:1-8; 29:36-37], and the golden Altar of Incense [see Exodus 30:1-10; Leviticus 4:7]. But what was the means of atonement carried out upon this earthly throne of mercy known as the "Seat of Atonement" to bind Israel the Bride to Yahweh the Bridegroom? Once a year, on Yom Kippur, the "Day of Atonement" [Leviticus chapter 16] the "mercy seat" served as the 3^rd holy Altar of Yahweh when the holiest of sin-offerings was sprinkled on the Kapporeth. In the ordinary sacrifices on ordinary days and during the days of the 7 Sacred Feasts of Yahweh, the blood of the sacrificed victims was sprinkled and then poured out at the corners of the great bronze Altar of Burnt Offerings in the courtyard of the Temple or sprinkled upon the horns of the golden Altar of Incense that stood in the Holy Place in front of the curtain woven with cherubim that separated the Holy Place from the Holy of Holies in which the Ark of the Covenant rested. The Ark of the Covenant was the highest or most holy of the altars of Yahweh for 3 reasons:

It covered the testimony of God contained in the two tablets of the 10 Commandments.
The glory of Yahweh rested upon it between the wings of the golden cherubim that overshadowed the Ark making it the earthly throne of God.
As the site of the atonement of Israel on the Feast of Atonement it became Yahweh's earthly "throne of grace", establishing the institution of atonement [given in Leviticus 17:11] and serving as the foreshadow of Christ's act of atonement when He served as both the sinless victim as well as the enthroned King on the earthly Altar and "Mercy seat" of the Cross.

Yahweh had promised in Exodus 20:24 that He would come down to Israel at the moment of sacrifice at the bronze Altar of Burnt Offerings in the courtyard of the Tabernacle/Temple and would, in the cloud of smoke that rose from the burning sacrificial victim, receive the offerings of the Covenant people both individually and collectively and recompense them by His blessings. But on the Altar of the "Seat of Atonement/ Mercy Seat" He did not come in the form of the visible rising cloud. Instead He came invisibly in a manner that could not be seen in the natural world but in a manner that required the obedient faith of the Covenant believers. God comes to us today in the same manner when Christ comes to us in the sacrifice of the Mass as He offers His perfect sacrifice sacramentaly in atonement for the sins of the world upon the Altar of every Catholic Church'. It is His invisible presence that comes to us on the altar as He manifests Himself through the power of God the Holy Spirit becoming present in what only appears to be bread and wine just as in the Yom Kippur [Feast of Atonement] sacrifice in ancient times this invisible miracle of atonement required the faith of covenant believers.