One topic that keeps coming backup is Baptists making the false claim that they've always existed (despite the lack of evidence, writings etc). Well here is a quote of one of the Anabaptist "creeds" (remember there were several rival groups called anabaptists in the "radical reformation")
The baptizer first testifies to the baptizand and asks if he believes in God, the Father, the Son, and the Holy Spirit. The baptizand confesses. He then is asked if he desires to yield himself to God to live for Him and His church. If so, he is told to kneel before God and church, and water is poured upon him. If baptism cannot be performed before the entire church, the baptizer may perform the ordinance alone.--Ridemann's Rechenschaft,1540: Article VII, The formula for Baptism
As is commonly known, Baptists INSIST on FULL immersion and NOT pouring. Yet, these Anabaptists in 1540 were fine with pouring, in fact they recommended it!
Here is another early Anabaptist confession:
Thereby shall also fall away from us the diabolical weapons of violence--such as sword, armor, and the like, and all of their use to protect friends or against enemies--by virtue of the word of Christ: "you shall not resist evil."--Schleitheim Confession (1527), Anabaptist, Article IV
These anabaptists were opposed to weapons of violence, unlike modern American Baptists (eg Southern Baptists) who are very fond of weapons of violence, particularly guns!
The fact is for the most part the descendants of the groups called anabaptists in the 15th and 16th century were are now called the Mennonites, Amish, and Unitiarian & Universalists. Obviously, the latter is not the same as the first two. In any case, the anabaptists of the 15th, 16th century were STARTED by ex-Catholics. Just as the other form of anabaptists were lead by people that were CATHOLIC. According to one reformed website modern day baptists descend from "particular baptists" that broke from the Anglican Church--they were originally more Calvinist is doctrine, then after coming to America conformed to the culture and resulted in a more Arminian form of Baptist theology. In the case of the Donatists of St Augustine's time, these "anabaptists" accepted all Catholic theology but held errors like baptisms performed by a sinful priest were not valid (therefore requiring "rebaptism).