From the Word
4 Rejoice in the Lord always; again I will say, Rejoice. 5 Let all men know your forbearance. The Lord is at hand. 6 Have no anxiety about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. 7 And the peace of God, which passes all understanding, will keep your hearts and your minds in Christ Jesus.
Philippians 4:4–7, RSV
Joy is the natural fruit of faith. Until the heart believes in God, it is impossible for it to rejoice in him. When faith is lacking man is filled with fear and gloom and is disposed to flee at the very mention, the mere thought of God. The unbelieving heart is filled with enmity and hatred against God. Conscious of its own guilt, it has no confidence in his gracious mercy; it knows God as an enemy to sin who will terribly punish the same. One may as well try to pursuade water to burn as to talk to such a heart of joy in God. All words will be without effect, for the sinner feels upon his conscience the pressure of God’s hand. The psalmist says, “Rejoice, ye righteous; and shout for joy, all ye that are upright in heart.” It must be the just and the righteous, then, who are to rejoice in the Lord. This text, therefore, is not written for the sinner, but for the saint. We must first tell the sinners how they can be liberated from their sins and perceive a merciful God. When they have been released from the power of an evil conscience, joy will naturally result.
But how shall we be liberated from an accusing conscience and receive the assurance of God’s mercy? He who would have a quiet conscience and would be sensitive of God’s mercy must place no hope whatever in works, but must comprehend God in Christ, comprehend the gospel and believe its promises. But what does the gospel promise other than that Christ is given for us, bears our sins and is our Bishop, Mediator and Advocate before God, and that only through him and his works is God reconciled, our sins forgiven and our consciences set free and made glad? When this sort of faith in the gospel really exists, the heart confidently feels his favor and grace. It is secure and in good spirits because God has conferred upon it, through Christ, superabundant goodness and grace. It will enjoy sincere pleasure in God as its beloved and gracious Father. Such is the rejoicing of which Paul here speaks — a rejoicing where is no sin, no fear of death and hell, but rather a glad and all-powerful confidence in God and his kindness.
Martin Luther and John Sander, Devotional Readings from Luther’s Works for Every Day of the Year (Rock Island, IL: Augustana Book Concern, 1915), 447–448.