In his second sermon for Trinity 24 in the Haus Postil, Luther observes that a primary purpose for preaching is to remind people that they are dying, and to drive them from their false security to the true security of faith in Jesus.
It is God's command to preach, so that people believe in him and cry out for his help: O Lord, preserve me from death! Be my Lord and God as the first commandment promises! The Sunday sermons are intended to proclaim this so that we might learn these truths. Moreover, that would be serving God acceptably when we laud and priase him, when we learn to have faith in him and speak of him according to the first commandment. We ought not act like thoughtless, brutish clods, like the peasants, burghers, and nobility of today who, though they see that they must die, nevertheless despise God and his Word, and succumb to death like cattle.
Surely an alarming attitude in the face of death's reality! They brashly despise God who offers them his grace. What? say these knaves, should I listen to the parson? Pass the beer, let us have a drink! O you shameful, miserable swine! Can you thus despise your Lord and God who so kindly invites you? You are impressed when your servant does something special for you, when your cow gives milk, when your horse gives you a ride, when your needs are met. But when your God and Lord wants to give you life, you despise and reject him, and try to keep him from speaking any longer to you in sermons; you have no desire to learn how to call upon him in time of need. I say it is disgraceful that our Lord God offers his help uselessly to people who beat against the wind, but have no other source of help. The result of such false security and despising of God will be that they coast along in the devil's name, until they come into hell and are lost eternally.