Original: The Mennonites are a group of Christian Anabaptist denominations named after the Frisian Menno Simons ( 1496 -- 1561 ) , who , through his writings , articulated and thereby formalized the teachings of earlier Swiss founders .
Simplified: In the last few decades some Mennonite groups have also become more actively involved with peace and social justice issues , helping to found Christian Peacemaker Teams and Mennonite Conciliation Service .