In the early church, new converts, referred to as "catechumens," were instructed (catechized) in the basic elements of the faith such as the Apostles' Creed, Lord's Prayer, and sacraments in preparation for baptism. During the fourth and fifth centuries, baptism had become a several-week-long rite leading up to the baptism on Easter. During this time, catechumens attended several meetings of intensive catechetical preaching, often by the bishop himself, and often accompanied by special prayers, exorcisms, and other rites. Catechumens recited the Apostles' Creed on Holy Saturday to show that one had completed catechetical instruction. By the sixth century, most of those presented for baptism were infants, and pre-baptismal catechesis was abandoned. The decline of preaching and education in general following the barbarian invasions also affected the decline of catechesis. Later, instructors (catechists) would teach Christians who had been baptized as children, to prepare for practicing the religion as thinking persons, both older children and adults. The term, catechism, used for a manual for this instruction, appeared in the Late Middle Ages. During this time the instruction was also expanded to include memorization of the Lord's Prayer and Apostles' Creed. Some clergy probably provided expositions of this material in addition to the Ten Commandments. The main function of catechesis during this period was preparation for confession by enabling the Christian to identify their sins.
Jean Gerson's L'ABC des simples gens was an important catechetical work published at the advent of the printing press. Along with Gerson's other catechetical works, it addressed the unique problems of teaching the faith to children. Sixteenth-century Christian humanists considered the reform of catechesis to be a high priority.Bishop of Basel Christoph von Utenheim, in one of the most successful efforts to revive catechesis, worked to have regular catechetical preaching instituted throughout his diocese. Johann Geiler von Kaisersberg was another popular preacher who followed the tradition of Gerson by preaching on the basics of the faith.
During the Protestant Reformation, the Reformers insisted that the Lord's Prayer and other forms be memorized in the vernacular languages of the people, rather than in Latin as was the practice among Roman Catholics. They wanted individuals to be able to fully understand the prayers. (Similarly, worship services were conducted in vernacular languages and Bibles and prayer books printed in vernacular editions.) The use of a question and answer format was popularized by reformer Martin Luther in his 1529 Small Catechism. He wanted the catechumen to understand what he was learning, so the Decalogue, Lord's Prayer, and Apostles' Creed were divided into small sections, with each followed by the question "What does this mean?"
Religious education continued to develop among both Catholics and Protestants.