The Sattlers joined up with the Anabaptist group and presented teachings that challenged those of the State, and of many protestant reformers. As this movement continued to grow, they faced horrendous persecution, and this video does NOT go light on the details of torture and execution (strong enough that I would not recommend this film for families with young children.)
What was interesting too, to me as an old Star Trek fan was seeing Mark Lenard (Spock's Dad) appear as Michael Sattler's nemesis. He's an excellent actor, and did a tremendous job in this role. Having seen him as a vulcan appealing to Klingons in the United Federation of Planets, it can be a little difficult seeing him outside of that role, but all the same, he does a great job.
The Radicals is a very moving film, and gives an excellent narrative of the early movement of the Anabaptists, their beliefs, and the horrendous persecution that they suffered from the catholic church. The DVD also includes some excellent extras, such as a documentary on the Anabaptists and chapter introductions setting the historical context. Worth checking out, but again, viewer discretion advised for the graphic torture sequences.
"Better a prison of stone than a prison of false conviction."