Rejoice in the Lord always; again I will say, rejoice. PHILIPPIANS 4:4
Joy Is a Result of Faith
This joy is a fruit and result of faith…. It is impossible for a heart to rejoice in God which does not first believe in Him. Where there is no faith, there is only fear, flight, timidity, and sorrow as soon as God is even thought of or named; indeed, there is hatred and enmity toward God in such hearts. The reason for this is that the heart finds itself guilty in its conscience and has no confidence that God is gracious and favorable, since it knows that God is the enemy of sin and horribly punishes it…. Therefore, this Epistle was not written for sinners, but for saints. The sinners must first be told how to be freed from their sins and receive a gracious God; then the joy will follow of itself when they are freed from their evil conscience…. St. Paul is here speaking about that kind of joy. There is no sin there, no fear of death or hell, but rather a glad and all-powerful confidence in God and His kindness.
From the Church Postil, sermon for Advent 4 on Philippians 4:4–7 (Luther’s Works 75:157–58) December 7
Luther, Martin. Day by Day:365 Devotional Readings with Martin Luther . Concordia Publishing House. Kindle Edition.