In the name of the Father and of the Son and of the Holy Spirit. Amen.
Welcome back to Purify the Heart. This is Pastor Zachary Courie. In Exodus 18, Moses received godly advice from his father-in-law, Jethro, to carry out the task of dealing with the burdens, the individual cases, of God’s people. Today, in Exodus 19, the people settle at the foot of Mount Sinai and Moses interacts with God on the mountain, revealing Himself to the people in awesome and terrifying ways.
Exodus 19
19 On the third new moon after the people of Israel had gone out of the land of Egypt, on that day they came into the wilderness of Sinai. 2 They set out from Rephidim and came into the wilderness of Sinai, and they encamped in the wilderness. There Israel encamped before the mountain, 3 while Moses went up to God. The Lord called to him out of the mountain, saying, “Thus you shall say to the house of Jacob, and tell the people of Israel: 4 ‘You yourselves have seen what I did to the Egyptians, and how I bore you on eagles’ wings and brought you to myself. 5 Now therefore, if you will indeed obey my voice and keep my covenant, you shall be my treasured possession among all peoples, for all the earth is mine; 6 and you shall be to me a kingdom of priests and a holy nation.’ These are the words that you shall speak to the people of Israel.”
7 So Moses came and called the elders of the people and set before them all these words that the Lord had commanded him. 8 All the people answered together and said, “All that the Lord has spoken we will do.” And Moses reported the words of the people to the Lord. 9 And the Lord said to Moses, “Behold, I am coming to you in a thick cloud, that the people may hear when I speak with you, and may also believe you forever.”
When Moses told the words of the people to the Lord, 10 the Lord said to Moses, “Go to the people and consecrate them today and tomorrow, and let them wash their garments 11 and be ready for the third day. For on the third day the Lord will come down on Mount Sinai in the sight of all the people. 12 And you shall set limits for the people all around, saying, ‘Take care not to go up into the mountain or touch the edge of it. Whoever touches the mountain shall be put to death. 13 No hand shall touch him, but he shall be stoned or shot; whether beast or man, he shall not live.’ When the trumpet sounds a long blast, they shall come up to the mountain.” 14 So Moses went down from the mountain to the people and consecrated the people; and they washed their garments. 15 And he said to the people, “Be ready for the third day; do not go near a woman.”
16 On the morning of the third day there were thunders and lightnings and a thick cloud on the mountain and a very loud trumpet blast, so that all the people in the camp trembled. 17 Then Moses brought the people out of the camp to meet God, and they took their stand at the foot of the mountain. 18 Now Mount Sinai was wrapped in smoke because the Lord had descended on it in fire. The smoke of it went up like the smoke of a kiln, and the whole mountain trembled greatly. 19 And as the sound of the trumpet grew louder and louder, Moses spoke, and God answered him in thunder. 20 The Lord came down on Mount Sinai, to the top of the mountain. And the Lord called Moses to the top of the mountain, and Moses went up.
21 And the Lord said to Moses, “Go down and warn the people, lest they break through to the Lord to look and many of them perish. 22 Also let the priests who come near to the Lord consecrate themselves, lest the Lord break out against them.” 23 And Moses said to the Lord, “The people cannot come up to Mount Sinai, for you yourself warned us, saying, ‘Set limits around the mountain and consecrate it.’ ” 24 And the Lord said to him, “Go down, and come up bringing Aaron with you. But do not let the priests and the people break through to come up to the Lord, lest he break out against them.” 25 So Moses went down to the people and told them. (Exodus 19:1–25, ESV)
This is the Word of the Lord.
Thanks be to God.
As Israel encamps before Mount Sinai, Moses ascends to God. The Lord speaks to Moses, declaring Israel to be His “treasured possession among all peoples” if they will listen to His voice and keep His covenant. He reassures them of His faithfulness by pointing to what He has already done: “I bore you on eagles’ wings and brought you to myself.”
The Lord then defines Israel’s identity and role in the world: they are to be “a kingdom of priests and a holy nation.” To be holy means to be set apart for God’s purposes, distinct from the nations around them. Their calling as a kingdom of priests means they are to intercede—not only for one another but also for the nations—acting as representatives of God to the world and bringing the burdens of others before the Lord in prayer. They are chosen, not for privilege alone, but to serve as mediators of God’s blessings to all people.
Israel responds to the Lord through Moses, saying, “All that the Lord has spoken we will do.” They commit themselves to the covenant, acknowledging God’s authority and their responsibility to live according to His will. Yet, as the story of Israel unfolds, their repeated failures will prove that their obedience cannot be sustained on their own strength. They need something greater than their own resolve—they need a Mediator beyond Moses. This is like when the apostles, especially Peter, adamantly refuse to deny Jesus, but quickly and easily fall into denial of him, because they’re unaware of their own weakness.
Back to Exodus 19: the Lord then announces that He will descend upon the mountain in a thick cloud so that the people will hear His voice and trust Moses as His chosen servant. He instructs them to consecrate themselves, including washing their garments, a purification in preparation to encounter the holy God. On the third day, the Lord descends upon the mountain, and the experience is terrifying. God reveals Himself in the midst of fire, smoke, thunder, lightning, an earthquake, and a long and “very loud” trumpet blast. The people tremble in fear. The sheer power and holiness of God make it clear—they cannot approach Him on their own terms. A mediator is essential. God commands that only Moses and Aaron may ascend, while the rest must keep their distance.
This scene foreshadows Christ, the greater Mediator. The people needed Moses to stand between them and God, just as we need Christ to stand in our place. Unlike Moses, who was a temporary mediator of the old covenant, Jesus is the eternal Mediator of the new covenant. He is not merely a prophet relaying God’s words—He is God Himself (God the Son specifically), who descended not to a mountain but into human flesh. While Mount Sinai showed the terrifying holiness of God that keeps sinners at a distance, Mount Calvary reveals the love of God that draws sinners near because there Christ endures the terror of God on our behalf. On another third day, Christ, who bore the fire of God’s judgment for us on the cross, rises from the dead, making a way for us to come to the Father without fear.
In Christ, we who were once far off are now called God’s treasured possession. We are made part of His kingdom of priests, not by our obedience to the law, but through His perfect obedience and sacrifice. St. Peter says of all Christians in 1 Peter 2:9-10, “You are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light. Once you were not a people, but now you are God’s people; once you had not received mercy, but now you have received mercy.”
In Christ, we are purified—not merely by washing our garments, but by being clothed in His righteousness in the waters of Holy Baptism. He is our pure garment, as St. Paul says in Galatians 3:27, “For as many of you as were baptized into Christ have put on Christ.” Now, through our great Mediator, we can approach God with confidence, knowing that the consuming fire of His holiness has been satisfied in the cross of Christ.
Let us pray. O God, whose glory it is always to have mercy, be gracious to all who have gone astray from Your ways and bring them again with penitent hearts and steadfast faith to embrace and hold fast the unchangeable truth of Your Word; through Jesus Christ, Your Son, our Lord, who lives and reigns with You and the Holy Spirit, one God, now and forever. Amen.
Let us pray. Almighty and everlasting God, You despise nothing You have made and forgive the sins of all who are penitent. Create in us new and contrite hearts that lamenting our sins and acknowledging our wretchedness we may receive from You full pardon and forgiveness; through Jesus Christ, Your Son, our Lord, who lives and reigns with You and the Holy Spirit, one God, now and forever. Amen.
Thanks for joining me to Purify the Heart! Tomorrow, in Exodus 20, the Lord speaks His Ten Commandments. Until then, grace be with you. Amen.
