It was, of course, the work of Satan to get man to break God's commandment and fall into sin. Our whole lives the work of the Devil is to get us to break God's holy Law. The Law of God is good and wise. It sets His will before our eyes! It teaches us how to glorify Him by having His Name and Word as our highest treasures. The Law of God teaches us to love our neighbor by doing good to them and not doing harm to them in all things. And Satan teaches us to break the Law of God. To ignore and despise it and to break those commandments. Then, the Law becomes for us a mirror, showing us our sin: teaching us how it is that we fall short of God's glory. Oh yes, it is a wicked work of the Devil to tempt us to sin and break the holy commandments of God. But he has come up with something much worse than that! Satan has a work that is more diabolical and wicked and terrible. He teaches people to try to use God's Law to save themselves! To make themselves right with God! To balance out their bad things by trying to do good things. In short, by teaching people not that the Law of God will punish you but that if you keep it, you can save yourself! And ever since he came up with that idea there have been TWO religions in the world. The first religion, the first faith, the first worship, is the promise of God to save sinners by sending them a Savior. But Satan has come up with his own religion: the promise that sinners can save themselves by trying to keep God's Law.
So St. Paul tells us that there are two mountains. These are the two religions of the world. There is Mt. Sinai where the Commandments were given. That is a mountain where the Lord reveals Himself in thunder and flame and smoke. It is the mountain where He hands down His holy Law and curses anyone who dares to break even the least of His commandments. Mt. Sinai is the mountain upon which the Lord is hidden but His wrath and anger against sin is there for all to see. One wrong move and the earth will open to swallow. Mt. Sinai gives the Word of God about what YOU must do. What you are forbidden from doing. How YOU must live. It is the mountain of God's demands and threats and judgment. Sinai stands as the towering reminder that God is holy and you are not. But the devil has convinced people to try to climb that mountain. To try and get to the Lord on the steps of His commandments. Break one, then keep one to make up for it. Do more good than bad. Earn God's favor. If you try hard enough to keep God's Law, he will let you climb up the path to Him on Sinai. But what do the Scriptures say? If anyone even an animal comes near the mountain, it shall surely be put to death! No, Mt. Sinai, where God's wrath are flaming and flashing, is not a mountain you want to get near. Don't even try!
But there is another mountain. Mount Zion. Mount Calvary upon which Jesus died for sinners. On that mountain, God is there, hidden in flesh. His wrath is there, hidden in the sufferings of Jesus. His punishment of sins is there, falling upon the Lamb of God. But on this mountain, sinners are saved. On this mountain, God's grace is shown. On this mountain, the Lord is forgiving. On this mountain, the promises of God are fulfilled. On this mountain, the Lord is doing for us. On Calvary, it is Jesus who speaks forgiveness and a promise of paradise to sinners. On this mountain, the Lord is saving and redeeming. This mountain is the mountain of mercy, of grace, of forgiveness, of righteousness and peace with God. On this mountain, the wrath of God is set upon Jesus and sinners are made once again acceptable to the Father. On this mountain, you cannot save yourself; Jesus does the saving. On this mountain, the Devil loses his power to accuse sinners. On this mountain, the power of death and sin is defeated. On this mountain, salvation is accomplished. On this mountain, the Lamb is sacrificed. On this mountain, Mount Calvary, the mountain of the cross, the mountain Jesus' death for sinners, sinners are saved. On this mountain, the peace of God is brought to the world.
Those who are of the Devil's religion, trying to save themselves by keeping the Commandments, they have Hagar, the slave woman for their mother. They are children whose mother cannot help them. When their cruel master, the Devil, tells them to save themselves by keeping the Law and then that they will die forever because they broke the Law, their mother cannot help them. Their religion will give them no comfort. Those who have Hagar for their mother are slaves, chained and shackled by the Law, whose cruel chains chaff and slice their flesh. Those who have Hagar for their mother persecute those who don't. They try to puff themselves up. They show how religious they are. How much better they are than others. They attack others who do not seem to try as hard, who do not follow their ways. They despise and speak badly of those who aren't as holy as they are, who aren't as religious or pious. They even physically attack and kill those who don't follow their ways. And in the end, those who have Hagar as their mother, will die in despair as Judas did, having nothing but themselves to save themselves from their sins and guilt. They run forth to keep the Law as if it will make them free and then with a wicked grin and evil laugh, Satan yanks the chains of his slaves and they are jerked back into death and despair. Because the Law cannot save them. They cannot save themselves. They will perish. Such are the religions that teach people to climb Mt. Sinai, to save themselves by the commandments of God or the rules of men and who have Hagar the slave woman as their mother.
But there is another mother. The mother of Isaac, the mother who is free: Sara. Who corresponds to the New and Heavenly Jerusalem, the Church. The Church is free because she is the bride of Christ. She is the mother of those who are born from her womb—the font—by water and the Spirit. Those who have the Church as their mother are those who are born not into slavery but into freedom by grace. Those who have the Church as their mother are those who have been born again, from above, at the font, by water and Word and Spirit. Those who have the church as their mother are those who are nourished and fed on the pure milk of God's Word and promises, the Word which gives us the pure sweet forgiveness and salvation of Christ. Those who have the Church as their mother are those who feast upon the body and blood of Jesus Christ. Those who have the church as their mother, are in the family of God by His grace, through the gifts that he gives in His Church. With Christ as their Brother and a heavenly Father, the free woman, the Church who is their mother gives them freedom. This is the mother who brings them up in fear, love and trust of God and who teaches her children to love and serve their neighbor. She is the one who comforts us when the bullies of this world, the Devil and his children pick on us and try to kill us. She is the one who tucks us in when the bedtime of our death comes, that we may fall asleep trusting confidently in the forgiveness of sins Jesus gives us. She it is who gives us, by Christ's means of grace, the faith with which our lamps are filled on the Last Day when our bridegroom comes. It is she, our mother, the church, us, who have eternal life with Christ, by His grace and mercy.
Dear children of God: You were born into this world as slaves of the Devil, children of Hagar, and knowing nothing but the religion of trying to climb up Mt. Sinai. But the Lord does not leave you in such slavery. He Himself comes in the flesh, Jesus Christ, to save you and rescue you. To do for you what you cannot do for yourselves. To save you. To redeem you. To give you a new birth, a heavenly Father, a mother which is the church, and a life and future with Him. The Devil teaches us to climb the mountain and then laughs when we fall. But in the true religion, the religion of the True God, the Son climbs the mountain for us, bearing His cross, to save us from sin and death. He gives us that salvation by the gifts of the Spirit who gives them to us by our mother, the church, from her womb and at her table which the Lord sets and furnishes. And Jesus raises us up on the Last Day. Rejoice, dearly baptized, for you are not slave children but free children in Jesus. The Lord has rescued us from the religion of the Law and brought us into the holy faith which clings to His grace. The Lord preserve us in that church and faith until He comes again. Amen.