The first three Commandments really belong together in governing your relationship with the Lord your God. It is a relationship of faith and love: of fear, love, and trust, as Dr. Luther describes it.
The First Commandments requires such faith in your heart, as the fountain of true worship, and the Second Commandment calls for the faithful confession of God’s Name with lips and mouth. But the Third Commandment directs you to the Word and work of God, who speaks to you by His Son and gives you rest in body and soul through His forgiveness of your sins and His gift of Life.
As the First Commandment is the foundation for all Ten, since all good works are done by faith — we should fear and love God so that we obey His Word and love our neighbor as He says — so is the Third Commandment the interpretive heart and center of the Law, because faith itself and all the good works of faith depend upon the preaching and hearing of God’s Word. There is no true faith in your heart, nor a right confession on your lips, except by the Word that He preaches.
The Third Commandment calls for the same fear, love, and trust in the Lord your God as the First, but as this faith is to be exercised in the world with your body and life, your time and energy; not by your working and doing, but, first of all, by your resting in what God does, by your listening to what God says, and by your receiving of what God gives to you in His Ministry of the Gospel. You worship the Lord by trusting Him with a kind of active passivity that looks to Him and relies upon Him for all good things. You quiet your mind and mouth to listen attentively to His Word. You set aside your own activities and pursuits, in order to avail yourself of His activity for you.
The Sabbath Command thus rests upon an implicit promise that God is the One who gives you life and provides for you all that you need for body and soul, for this world and the next. He is the One who upholds the world and gives it life by the power of His Word. It does not depend on you, nor do your own body and life depend on you, but you and all depend upon the Lord who loves you.
You do have your work to do, as God has called and stationed you to perform according to His Word, within your family and community, and within the fellowship of His Church on earth. But even this is the work of the Lord your God, who chooses in love to care for His Creation by the ways and means of His own Creation: from the majestic holy angels to the men and women whom He calls and positions in various walks of life; from the plants and animals that feed and clothe us, to the sun that shines, the rain that falls, the dirt beneath our feet, and the air that we breathe.
You honor the governing authorities, for example, beginning with your father and mother, as per the Fourth Commandment, because you trust that God is the One who stands behind these people; that He has provided them for you, for your good; that He catechizes and disciplines you by their words and works; and that He accomplishes His own purposes through them. Instead of living as a law unto yourself, you rest yourself in God, and you submit to those He has placed over you.
The Sabbath Command also rests upon the promise of the Lord that He will not keep silent, that He will not be absent, but that He will continue to speak, to preach and teach, to catechize His people with His Word and Spirit, and to bestow His gifts by the ways and means of His Gospel. It is in this promise that you wait upon Him, you rest yourself in Him, and you rely upon Him.
In particular, it is the incarnate Son of God, Christ Jesus, who actually is your Sabbath Rest. For He is your Savior, who delivers you from sin and death and every evil, and who brings you into the safety, peace, and rest of everlasting life with God. Already now in the desert wilderness, and hereafter for eternity in Paradise, He is the Bread of Life, the living and Life-giving Bread from heaven, who feeds you with Himself in both soul and body. He is not a Law for you to keep, but a Gift of God for you to receive. Your faith and life thus rest upon Him, upon His faithfulness.
Your love for God (above all else) and for your neighbor (as yourself), in accord with all of God’s Commandments, proceeds from your Sabbath Rest in Jesus Christ.
Your love for God begins with the faith in your heart that is worked in you by the preaching of the Word of Christ, and with the right use of His Name as the Second Commandment requires:
You pray, praise, and give thanks to God in Christ Jesus on the basis of His great Salvation. You confess and call upon His Name, as He has revealed and given His Name to you in your Baptism; which is to say that you speak to and about the Lord Jesus as He has spoken to you by His Word and the preaching of it. You say the same thing that He has said. And, with your speaking of His Word, you also act as He has acted. You live before God, and for your neighbor, as Christ lives.
As He gives you rest in body and soul with His Word of the Gospel, and in His Holy Sacraments, so do you give rest to your neighbor by your gracious words and with your charitable works of mercy. Most especially that includes the forgiveness of your neighbor’s trespasses against you. In all respects, you love your neighbor, not only as yourself, but in the way that Jesus loves you.
Live rightly (in keeping with God’s Word), and not wrongly (in disobedience to His commands), because you are in Christ Jesus. In Him alone is your life and your salvation, your peace and rest forevermore. You are in Him, and He in you, because He speaks to you and gives Himself to you.
The holy life to which He calls you — a life comprising faith toward Him and love for Him and for your neighbor — is not a means of gaining a righteousness of your own by the works of the Law. It is rather to live righteously by the grace of God in Christ Jesus, by faith in His Word of the Gospel, His forgiveness of sins. It is to live by the Lord’s own keeping and fulfillment of His Law for your salvation. For He is the completion and perfection of the Ten Commandments, who in holy faith and holy love, as true God and true Man, has reconciled you to His God and Father, atoning for your sins by His sacrifice upon the Cross, and justifying you with His Resurrection.
The Lord teaches you to live in this way, according to His holy and righteous will, because it is good and right, and because it is good for you; lest, by departing from His Way, from His Word and work of the Gospel in Christ, you lose the life that He desires for you and gives to you.
In much the same way that the Second Table of the Law protects your neighbor from the harm that you would do to him, so do the first three Commandments protect you from the harm that you would do to yourself. For the constant temptation is to live unto yourself, as a god unto yourself, in splendid isolation from your neighbor and his needs, and without the Word of God in the world. As though you could actually make a name and a life for yourself. As though you did not need the Ministry of His Gospel as much or more than your body needs food and drink and oxygen to live.
The truth is that trying to make a life for yourself only robs you of life. It wears you out and ruins you in body and soul. But God calls you to rest yourself in Christ Jesus, so that, by His grace, through faith in His Gospel–Word and Sacraments, you have peace and rest even in your labors.
The point and purpose of genuine fasting, therefore, is that you would cease and desist from the desire and effort to feed yourself, in order to be fed by God, to eat and drink from His open hand. Thus fasting from your own desires, you feast upon Christ in faith and with thanksgiving.
Where you have not lived in this way — where you have not trusted and relied upon the Lord your God by seeking out His Word and receiving His good gifts — where you have gone your own way, instead of keeping His Commandments — repent of your sins, and return to the Lord your God.
Remember the Sabbath Day by keeping it holy; that is to say, not Saturday per se, nor even Sunday as one day out of seven, but remember the true and permanent Sabbath that is yours in Christ Jesus. Rest yourself in Him, and remain in Him, by listening to His Word and the preaching of it, daily returning to the significance of your Baptism, and availing yourself of the Sacrament. Delight yourself in these means of grace, as the Lord Himself delights in you by these very same means.
Rest yourself in the Lord of the Sabbath, and be at Peace in Him, for He remembers you in mercy. He remembers you, not simply with faraway thoughts and emotions, but with His active presence, and with His Word and works of love for you, and with the gift of His own flesh and blood.
As He has fulfilled the entire Law for you in love — on your behalf and for your eternal benefit — so does He do you no harm, but He helps you in every way. He daily and richly provides you with all that you need, unto the resurrection of your body and the life everlasting in His Body.
With the preaching of His Gospel, with Holy Absolution, and with His Body given and His Blood poured out, He forgives you all your sins, and He gives you life in place of death and damnation. That precious good news and free gift of God in Christ Jesus stands fast and secure against all the weariness and wickedness of this old world, so that you are not undone or destroyed; you are not worn out or left to waste away in melancholy grief or hopeless despair, but you are raised up and refreshed in your body and soul, in heart, mind, and spirit, in the Resurrection of Christ Jesus. Assuredly, He is your Peace and Sabbath Rest, now and forevermore.
In the Name + of the Father and of the Son and of the Holy Spirit. Amen.