I tend to use a fair amount of extra-biblical quotations in my preaching. I don’t know if I use too many or too little, but here are four reasons I find quotations in sermons to be helpful.
First, there are times when I cannot state a truth any better than someone else has stated it. My goal as a preacher is to uncover the meaning of a text, present that meaning to my audience and then help that audience understand the value and application of that text. A quotation from an extra-biblical resource (e.g., commentary, non-fiction book, blog, etc.) may better state or explain something than I am capable of. A memorable quote can stay with someone for a long time. For example, “What comes into our minds when we think about God is the most important thing about us” (a quote from A.W. Tozer in Knowledge of the Holy) has helped me more than any other statement outside of Scripture. The phrase “most important thing about us” is what singed this statement into my conscience. Because of this statement, I have come to realize that your view of God informs everything about your life.
Second, I value the opportunity to introduce my audience to good resources for spiritual growth. Yes, the Bible is the primary and authoritative source for biblical truth, but if someone has the time to read outside of the Bible, I want them to have a “go to” section in their minds of books on certain topics. If I can reference those books or authors often in my preaching, they will quickly be able to go to trustworthy sources for edification and instruction. For example, when someone wants to be more proactive in their pursuit of holiness, I want them to consider J.C. Ryle’s book entitled Holiness; thus, I reference that book as I am able in my preaching. When someone wants to grow in their understanding of the sovereignty of God, I want them to consider Jerry Bridges’ book Trusting God; thus, I reference that book as I am able in my preaching.
Third, it is helpful to know that when you preach truth you are not alone. Using an extra-biblical quotation adds authority to your preaching. If you stand in a long line of men and women before you who have preached the same truths, then your audience will feel more confident in the orthodoxy of what you are teaching them. If you share the exact words of St. Augustine or Charles Spurgeon or Martin Luther, then your preaching becomes that more vital to hear, because you are preaching the same message they preached, and that adds authority to your preaching.
Finally, I read a lot; so, I feel an obligation to share a lot of what I read. Being a good steward of what you read not only means you use the truth in your own life, but you find ways to provoke and stir up others to love and good works with the truths you have recently read. Right now, I am reading a short book by R.C. Sproul entitled Does Prayer Change Things? While I have not “learned” anything new about the effect of prayer, I am already beginning to think of others I know who struggle with prayer and don’t see it’s purpose considering the sovereignty of God. I am eager to share statements by Sproul with them and later in my preaching in the Sermon on the Mount (e.g., the passage I begin teaching in 2017) to help the prayerless Christian feel more confident in their prayer life.