The late medival world in upheaval and spinning out of control was depicted by Werner Tübke in an enourmous paining "Early Bourgeois Revolution in Germany" in the dying days of the so-called German Democratic Republic. The revolutionary Thomas Münzer is at the centre, while Dr. Martin Luther is but on the periphery even if right in front. Probably it is rather realistic as Dr. Martin Luther, who had occupied centre stage in Worms was still an outlaw and excommunicated heretic, sidelined in the powerplay of the ruling forces of the time, who were continuously occupied elsewhere thus giving the Reformer much needed time to work out the detailed consequences of the rediscovered gospel and get the mustard seeds of this explosive message planted, growing, established and flourishing.
Still, in the first decade of the Reformation everything was still very much in flow. The pure gospel of the Christian's freedom was severely contested and it was an uphill struggle all the way. Firstly, the impatient peasants were sick and tired of waiting for better days, which they felt they had deserved long time ago. They were no longer willing to wait for their powerful adversaries amongst the nobility to concede them their god-given rights and freedoms. Then there were the left-wing reformers, who were throwing out the baby with the water, enthusiastically going iconoclastic, anti-sacramentarian, fundamentalistic - basically balistic. Forbidding all that was not written. Willing to forgo the centuries of Church history by promising heaven on earth - like that frightful experiement of "König- und Himmelreich zu Münster", which went so horribly wrong. Lastly by the Erasmian intellectuals, who preferred sitting on the fence rather than chosing sides in the spiritual warfare boiling over on all sides. Trying to placate all, they landed up at odds with everyone. It was in this tumultous time, that Dr. Martin Luther, who was personally deeply engaged in all of these profound struggles trying to address the most pressing issues in stupendous volumes of preaching, teaching and writing, was pushed and prompted by his colleagues to come up with something helpful for the disasterous conditions of the Saxon parishes and congregations. Luther himself had witnessed this obvious calamity of ignorance and blantant paganism during the Saxon-Visitation and felt the pressing urgency weighing down on him very much. So, he came up with the Catechisms. Two of them. The bigger one titled "Large Catechism" was a collection of sermons preached following the lectionary for catechetical instruction in St.Marys on weekdays and in special series for lent etc. The shorter one "Small Catechism" was a singular masterpiece in its brevity, clarity and convincing faithfulness. No wonder friend and foe used it as the benchmark in Christian mission practice as Nikolaus Selnecker points out with reference to the reactionary and counter-reformational Jesuits in the Far East.
Dr. Martin Luther was by no means the first to write a German catechism, nevermind a basic Christian primer containing "all that a Christian needed to know for salvation" in ran under the title: "regula fidei" (Rule of faith). We know it from the apostolic "Didache" (Teaching) and St. Augustines "de catechizandis rudibus" (Instruction of the unlearned). Luther's contributions were but the latest commentaries of those main and regular constants of faith throughout the changing times and contexts, which the Church had received from the living Lord God and Father all the way back to those days of his prophet Moses on Mt. Sinai. At his ascension the Lord God Jesus Christ had entrusted his disciples to teach everything he had taught them even as he consoled them with the promise of the coming Comforter, his Holy Spirit, who would himself remind them of everything he had taught them up to date. The chief articles of the Christian faith, the pillars of our salvation and the foundation of our conviction, trust and joyous confession are these holy standards and constants in context (Bevans & Schroeder), which the triune God himself has given to his church. Luther takes up the traditional five main biblical parts and elucidates them using didactic genius and lingustic artistry to compile a Christian handbook, that is still immensely practical, relevant, helpful besides being impressive and easy to memorize in its expressive beauty. No small wonder, that it used so widely today in catechetical instruction of baptismal candidates on the misson field, but also for the basic foundation of confirmands and as guideline and prayerbook for those, who with all sincerity would like to be true and faithful Christians.
The five main parts of the Christian Catechism are: The 10 Commandments given to Moses at Mt. Sinai (Law), the Apostlic Creed (Gospel) devided into three main articles concerning creation, salvation and sanctification, the Lord's Prayer plus the 2 sacraments: Holy Baptism and the Lord's Supper with the final volume on Confession & Absolution with pastoral questions regarding Christian life.
For the study of Luther's Small and Large Catechism we will use the translated versions online for both the Small Catechism and the Large Catechism. Obviously Luther's catechetical hymns will feature too, just as the illustrations he summond by Lucas Cranach etc. This calls to mind his own reference in the Smalcald Articles of God's richness in mercy and goodness that he gives us such ample and diverse examples of the gospel - so too of the main articles of Christian faith.
The standard secondary literature is the magesterial set of 5 volumes by the Heidelberg theologian Albrecht Peters, which has been translated most ably into English by amongst others T.H.Trapp. Yet the historical masterpiece of Johann M. Reu on Luther's Catechisms deserves a special mention too. Other helps are plentiful and only a few are pointed out below.