Luther's major departures from Roman Catholic doctrine rest on these beliefs: the Scriptures contain the one necessary guide to truth, and it is the right of the individual to reach God through them with responsibility to God alone; salvation comes through faith alone, available to humanity through the redeeming work of Christ; and the sacraments are valid only as aids to faith. The principal statements of faith are found in Luther's two catechisms, the unaltered Augsburg Confession, the Apology of the Augsburg Confession, the Schmalkald Articles, and the Formula of Concord. These are all included in the Book of Concord (1580). Baptism was necessary for spiritual regeneration, but no form was specified. The sacrament of the Lord's Supper was retained, but the doctrine of transubstantiation was rejected.
As to the manner of worship, Luther chose to retain altars and vestments; he prepared an order of liturgical service, but with the understanding that no church was bound to follow any set order. There is today no uniform liturgy belonging to all branches of the Lutheran body; characteristically, however, an important place is given to preaching and congregational singing.
Because of Luther's conservatism and the political conditions of 16th-century Germany, the Lutheran churches originated as territorial churches, subject to the local princes. The local organization still has the most important place in church polity, but there is a growing tendency toward a more organized church.
Lutheranism has traditionally stressed education, and there are many Lutheran schools, colleges, and seminaries throughout the world. Since the mid-18th cent., Lutherans have had a program of Christian service for women called the Deaconess movement. The world membership of Lutherans is nearly 74 million.