In Christianity, a sermon is typically identified as an address or discourse delivered to an assembly of Christians, typically containing theological or moral instruction. Although it is often called a homily, the original distinction between a sermon and a homily was that a sermon was delivered by a clergyman (licensed preacher) while a homily was read from a printed copy by a layman. In the 20th century the distinction has become one of the sermon being likely to be longer, have more structure, and contain more theological content. Homilies are usually considered to be a type of sermon, usually narrative or biographical, see sermon types below.
The word "sermon" is used to describe many famous moments in Christian (and Jewish) history. The most famous example is the Sermon on the Mount by Jesus of Nazareth. This address was given around 30 AD, and is recounted in the Gospel of Matthew (5:1–7:29, including introductory and concluding material) as being delivered on a mount on the north end of the Sea of Galilee, near Capernaum. It is also contained in some of the other gospel narratives.
During the later history of Christianity, several figures became known for their addresses that later became regarded as sermons. Examples in the early church include Peter (see especially Acts 2:14b–36), Stephen (see Acts 7:1b–53), Tertullian and John Chrysostom. These addresses were used to spread Christianity across Europe and Asia Minor, and as such are not sermons in the modern sense, but evangelistic messages.
The sermon has been an important part of Christian services since Early Christianity, and remains prominent in both Roman Catholicism and Protestantism. Lay preachers sometimes figure in these traditions of worship, for example the Methodist local preachers, but in general preaching has usually been a function of the clergy. The Dominican Order is officially known as the Order of Preachers (Ordo Praedicatorum in Latin); friars of this order were trained to publicly preach in vernacular languages, and the order was created by Saint Dominic to preach to the Cathars of southern France in the early 13th century. The Franciscans are another important preaching order; Travelling preachers, usually friars, were an important feature of late medieval Catholicism.
In most denominations, modern preaching is kept below forty minutes, but historic preachers of all denominations could at times speak for several hours, and use techniques of rhetoric and theatre that are today somewhat out of fashion in mainline churches.
During the Middle Ages, sermons inspired the beginnings of new religious institutes (e.g., Saint Dominic and Francis of Assisi). Pope Urban II began the First Crusade in November 1095 at the Council of Clermont, France, when he exhorted French knights to retake the Holy Land.
The academic study of sermons, the analysis and classification of their preparation, composition and delivery, is called homiletics.
A controversial issue that aroused strong feelings in Early Modern Britain was whether sermons should be read from a fully prepared text, or extemporized, perhaps from some notes. Many sermons have been written down, collected and published; published sermons were a major and profitable literary form, and category of books in the book trade, from at least the Late Antique Church to about the late 19th century. Many clergymen openly recycled large chunks of published sermons in their own preaching. Such sermons include John Wesley's 53 Standard Sermons, John Chrysostom's Homily on the Resurrection (preached every Easter in Orthodox churches) and Gregory Nazianzus' homily "On the Theophany, or Birthday of Christ" (preached every Christmas in Orthodox churches). The 80 sermons in German of the Dominican Johannes Tauler (1300–1361) were read for centuries after his death. Martin Luther published his sermons (Hauspostille) on the Sunday lessons for the edification of readers. This tradition was continued by Chemnitz and Arndt and others into the following centuries—for example CH Spurgeon's stenographed sermons, The Metropolitan Tabernacle Pulpit. The widow of John Tillotson (1630–1694), Archbishop of Canterbury received £2,500 for the manuscripts of his sermons, a very large sum.
"The certain mark by which a Christian community can be recognized is the preaching of the gospel in its purity." – Luther
The Reformation led to Protestant sermons, many of which defended the schism with the Roman Catholic Church and explained beliefs about the Bible, theology, and devotion. The distinctive doctrines of Protestantism held that salvation was by faith alone, and convincing people to believe the Gospel and place trust in God for their salvation through Jesus Christ was the decisive step in salvation.
In many Protestant churches, the sermon came to replace the Eucharist as the central act of Christian worship (although some Protestants such as Lutherans give equal time to a sermon and the Eucharist in their Divine Service). While Luther retained use of the lectionary for selecting texts for preaching, the Swiss Reformers, such as Ulrich Zwingli, Johannes Oecolampadius, and John Calvin, notably returned to the patristic model of preaching through books of the Bible. The goal of Protestant worship, as conditioned by these reforms, was above all to offer glory to God for the gift of grace in Jesus Christ, to rouse the congregation to a deeper faith, and to inspire them to practice works of love for the benefit of the neighbor, rather than carry on with potentially empty rituals.
One early female writer of sermons in England was Mary Deverell (1731–1805).
In the 18th and 19th centuries during the Great Awakening, major (evangelistic) sermons were made at revivals, which were especially popular in the United States. These sermons were noted for their "fire-and-brimstone" message, typified by Jonathan Edwards' famous "Sinners in the Hands of an Angry God" speech. In these sermons the wrath of God was intended to be made evident. Edwards also preached on Religious Affections, which discussed the divided Christian world.