Anabaptists believed that only adults could willingly accept
Christianity and therefore sought to rebaptize adults so the may be saved.
Like most other Protestant sects the anabaptists took the Bible with absolute faith, and in the beginning Luther's teachings.
Anabaptists lived in small, independent communities with each other.
Also believed in the separation of church and state, which made them very unpopular with the local monarchs of the time (remember this was when church and state were regarded as pretty much inseparable). At the same time they practiced absolute pacifism, which could not have helped with the constant persecution by government authorities. Finally, they believed in communal property.
Viewed as highly dangerous by the government (in a thought crime way, of course).
Their beliefs attracted primarily the poor, uneducated, and unemployed.
The anabaptists would later go on to influence sects such as the Quakers, Baptists, mennonites, Congregationalists and the framers of the Constitution