This is the "speech" given by the minister after the Bible readings Through the sermon, the minister helps us apply the lessons of the Bible to our every day lives (not to be confused with a "homily" which can be on any moral subject, and is usually quite short )
A sermon is a talk on a religious or moral subject that is given by a member of the clergy as part of a church service
a moralistic rebuke; "your preaching is wasted on him" an address of a religious nature (usually delivered during a church service)
Specifically, a discourse delivered in public, usually by a clergyman, for the purpose of religious instruction and grounded on some text or passage of Scripture