Here are helpful notes by my preaching professor Alex Montoya on why sermons fail. These notes are also adapted from Biblical Preaching for Today's World by Lloyd Perry.
1. The preacher does not know how to distinguish between an essay and sermon.
Writing and preaching are two different things. A preacher who just reads his notes, without understanding basic public speaking principles will bore the congregation. A preacher must preach to the listening ear. He must repeat, repeat, and repeat his points. He must maintain proper eye contact and not be monotone.
2. The preacher elaborates the obvious.
The preacher simply repeats the text. However, an expositor will spend time explaining and applying the text. This is where hard work and study comes in. The preacher must know the historical, cultural, political, and geographical background of the text. He must know the grammar and syntax of the text. He must understand the authorial meaning of the text. In other words, he must understand the text himself so that he would be able to help the congregation understand the text.
3. The preacher does preach with a purpose.
He has no main proposition, no thesis, or no purpose for preaching the text. The text must have a driving theme or proposition that the preacher is seeking to communicate. If your wife wakes you up at 3am in the morning, you should be able to tell her what you are preaching on the following morning. If you don't know what your preaching, the congregation won't know what your preaching.
4. The preacher expects too much from the audience.
The preacher data-dumps 30 hours of his preparation upon his listener. He gives 50 reasons why a first century boat was important to the text or he explains 10 reasons why the hiphil imperfect verb is important. He is like a fire-hydrant showering his poor listeners. Preachers must understand that they will probably only deliver 20 % of what they actually studied during the week.
5. The preacher assaults the will of the audience.
He preaches "down" at them. He preaches as if his people are "inferior," "stupid," "ignorant", or not "biblically trained." Instead, a preacher ought to have a heart of compassion to whom he preaches. Martin Lloyd Jones has rightly said, "It is one thing to love preaching, but it is another thing to love those to whom you preach." The preacher should always ask his listeners, "Did I help you with the truth of God's Word?" The preacher must preach from compassion, not pride.
6. The preacher tries to "get" without "giving."
Preachers must earn the right to preach. They must "work" the room to see who are their listeners. Preachers will labor hard to have interesting introductions and build rapport with the congregation. If you want your sermons to fail, isolate yourself and never interact with your people. If you want your sermons to succeed, make sure you are involved with the people of your congregation.
7. Preachers fail to recognize the limited power of listening.
Expository preaching demands a higher level of listening. However, we live in a facebook, 120 character tweet, tumblr digital world. We live in world that communicates information through the media rather than through insightful and engaging books. Therefore, a preacher must have an outline for his text and a main idea for his text to help his listeners know where he is going.
8.The preacher does not know the technique of persuasion.
The preacher needs to create the need of the biblical passage and seek to apply the passage to the congregation. Simply put, he must preach! He must demand a verdict! He must call for a commitment! He must confront theological or moral error! He must exhort, rebuke, correct, and teach with all patience!
9. The preacher fails to illustrate.
All great preachers use illustrations. The Lord Jesus used the illustration of birds and flowers to teach us not to worry. The apostle Paul taught us that we must endure in the ministry as a good soldier and athlete of Christ Jesus. Illustrations provide "color" and "flavor" to the congregation. The Bible is full of illustrations. If you want your sermon to fail, make sure you teach your people abstract concepts without illustrating.
10. The preacher fails to preach extemporaneously.
If you want your sermon to fail, just read your notes without any eye contact. Reading your sermon is a preaching sin Montoya tells us. Preaching is an event where you engage the congregation with the truth of God's word. If you are simply reading your manuscript while neglecting the people you preach to, you have failed to engage and preach to the audience. The preacher should avoid being monotone, stiff, and boring!
