Law, gospel, and prayer are the chief elements of the Christian faith according to the Scriptures. Luther calls the law and the gospel the “arguments,” that is, the fundamentals necessary for an understanding of the Scriptures; they represent the real content of the Scriptures. The law and the gospel constitute the ﬁrst two parts of the Catechism. Only one who knows the law and the gospel knows how to speak of God rightly, knows what God intends to say in the Scriptures. Then comes prayer as the third part. Prayer is the expression of the new situation and attitude of man in the presence of God, the attitude of the man who has allowed the law and the gospel to be addressed to him and accepted them in faith.
Herbert Girgensohn, Teaching Luther’s Catechism, John W. Doberstein, trans. (Philadelhia: Muhlenberg Press, 1959), p. 4.