The Deceiver can magnify a little sin for the purpose of causing one to worry, torture, and kill oneself with it. This is why a Christian should learn not to let anyone easily create an evil conscience in him. Rather let him say, "This error and this failing pass away with my other imperfections and sins, which I must include in the article of faith: I believe in the forgiveness of sins.
Martin LutherIf the devil were wise enough and would stand by in silence and let the gospel be preached, he would suffer less harm. For when there is no battle for the gospel it rusts and it finds no cause and no occasion to show its vigor and power. Therefore, nothing better can befall the gospel than that the world should fight it with force and cunning.
Martin LutherThe devil, the originator of sorrowful anxieties and restless troubles, flees before the sound of music almost as much as before the Word of God....Music is a gift and grace of God, not an invention of men. Thus it drives out the devil and makes people cheerful. Then one forgets all wrath, impurity, and other devices.
Martin Luther