Luther wrote the Small Catechism in 1529 after visiting Saxon parishes as part of an official inspection and finding, in his own account, that ordinary people and even many pastors could not recite the Ten Commandments, the Creed or the Lord's Prayer, let alone explain them. His response was not a treatise but a manual scaled to the household. It sets out six chief parts, the Ten Commandments, the Apostles' Creed, the Lord's Prayer, the sacrament of baptism, confession, and the sacrament of the altar, with a table of duties added for various stations in life. Each part is stated first in bare form and then explained through a repeated question, what does this mean, followed by Luther's own answer in short declarative sentences meant to be memorized word for word rather than paraphrased.
The explanation of the Creed's third article, for instance, states plainly that a believer cannot come to faith by their own reason or strength but is called by the Holy Spirit through the gospel, compressing Luther's larger theology of grace into a form a child could learn by heart. The head of every household, not the parish priest alone, was charged with teaching it daily, which is why later Lutheran tradition calls it the layman's Bible in miniature rather than a clergy manual.