There are a few methods weekly preachers use to get away with very little or no preparation:
- Reuse something old. These preachers have a storehouse of decades of sermons, and maybe even systems for how to make sure they don’t repeat them too often.
- Reuse something recent. Often the preacher has had another significant teaching opportunity during the week which becomes the message. e.g.: youth talk, funeral message, small group bible study.
- Plagiarize . Grab a bit of Piper, maybe some parts of the John Stott commentary – instant sermon.
- Extemporize. Some preachers who are generally immersed in the Word and are sharp minded can give great messages with little to no preparation. For example, George Whitefield.
- Short-term Biographical. Many preachers have mastered the art of building a message around the most significant event or encounter they had that week. “At Bunnings this week I said to the cashier…”
- Long-term Biographical. “In the good old days of the church, when men were men, we did X, Y, Z.”
- Hobby horse rotation. These preachers boil every sermon down to one or two doctrines (often denominational distinctives) and two or three applications (“pray”, “evangelise”, “trust God”). Once you have mastered the art of ad-libbing any text to these favourite themes you really don’t need much preparation.
I don’t actually think these are always bad. For example, there is a valid tradition within evangelicalism of reading other peoples sermons in the pulpit, just as there is a strong tradition of extempore preaching (especially on streets). Some people have unique gifts.
But generally speaking I believe if you rely on these methods you will spiritually starve yourself and your hearers, even if you have sound doctrine. It is very risky and poisonous in the long run.
The preachers I know who give outstanding low preparation sermons are those who spend 90% of their time giving extremely well prepared sermons.