God is not a God of sadness, death, etc., but the devil is. Christ is a God of joy, and so the Scriptures often say that we should rejoice ... A Christian should and must be a cheerful person.
Martin LutherFaith is a living, bold trust in God's grace, so certain of God's favour that it would risk death a thousand times trusting in it. Such confidence and knowledge of God's grace makes you happy, joyful and bold in your relationship to God and all creatures. The Holy Spirit makes this happen through faith. Because of it, you freely, willingly and joyfully do good to everyone, serve everyone, suffer all kinds of things, love and praise the God who has shown you such grace.
Martin LutherOne thing, and only one thing, is necessary for Christian life, righteousness, and freedom. That one thing is the most holy Word of God, the gospel of Christ.
Martin Luther