Walter Klaassen gathered and translated this comprehensive book of selections drawn from writings and statements of 37 sixteenth-century Anabaptists. The selections are arranged under topics such as Baptism; Church; Nonresistance; Jesus the Word; Government; Cross, Suffering, and Discipleship; and Relations to Other Christians.
This probably the best resource for understanding the early Anabaptist movement. The book has selections by different Anabaptist writers organized topically with good introductions to each section.
Here are a few thoughts of mine:
1. My interest in this is my research into the connection between Baptists and Anabaptists. It seems undeniable that these two groups are heavily connected, although they did not always get along. If we define Baptists theologically, the Anabaptists were the first to reject infant baptism, some of them even advocated baptism by immersion (Bernhard Rothmann and Pilgram Marpeck). Anabaptists were the first to insist on separation of church and state, although many insisted that Christians should not participate in the government at all, where Baptists did not go that far. However, Anabaptists are decidedly non-ritualistic when it comes to baptism, and Baptists could learn to be less so. Anabaptists stress that baptism is anchored in regeneration and taking up Christ-like character, without such, the act of baptism, however performed, is worthless. This is something Baptist should take into mind if they should seek to exclude someone sprinkled.
2. What is interesting about this early movement is its discernible similarity yet distinct diversity. Anabaptism, by this intrinsic diversity, provides a platform for ecumenism (despite some of their polemics against Catholics and Protestants) where it is able to see goodness in multiple expressions of the faith.
3. Anabaptists are predominately ethically minded and practical thinkers. Their theology demonstrates a kind of theological pragmatism, reflecting on issues like ethical institution of the sacraments, non-violence, suffering and witness, etc. over issues like theologies of election, etc. Their Christology and the atonement flow directly into the call of the Christian to emulate and imitate Christ, taking up the way of the cross. The modern exemplar of this would obviously be Yoder's Politics of Jesus.
Moreover, Anabaptist understandings of ethical action being integral to faith is important. I find reformed that Lutheran views of this terribly deficient, creating the possiblity of faith that is reduced to doctrinal assent without action. Christians are Christians because they are called to act like Christ! For the Anabaptists, obedience and taking up the way of Christ are not at odds with grace. Following Christ is embodying grace, as the law is lived in and through Christ's example and his commands of the law of love.
4. The western world owes Anabaptism a great deal of gratitude in regards to two values that began with the Anabaptists: (1) liberty of conscience and freedom of religious expression allows for people to believe and think freely, different from the religion of the state. (2) They insisted that beliefs should not be imposed by the sword. The political value of Anabaptist pacifism for questioning the need for "redemptive" violence.
Klassen has a small introduction to Anabaptism, which is hard to find. Those interested in Anabaptist theology should read the Systematic Theology of James McClendon. John Howard Yoder is the foremost ethicist and ecclesiologist of Anabaptism, and his books Politics of Jesus, the Royal Priesthood, and the Priestly Kingdom are excellent. J. Denny Weaver is an interesting theologian who has argued for a non-violent view of the atonement and theology proper, thus offering uniquely Anabaptists contrbutions to systematic theology. Simiarly, C. Norman Kraus' book on CHrist our Savior shows the veracity of thinking about Christology without recourse to the metaphysical assumptions of the creeds.