“The 90 to 13 ratio means this: preach at a level where 90% of what you say is intelligible to a 13 year old.
Two former colleagues of mine, who earned their M.Div. at Trinity, independently recounted to me that preaching tip Don Carson told them. He said he aims 90% of what he says in his sermon to be understood by a junior high student. This doesn’t mean that he “dumbs down” his content, it means that he speaks in a less technical manner.
Can the 13 year olds in your church track with your sermons?”