Birthler grew up in East Germany and was active in child and youth work for the Church, first in her parish in Prenzlauer Berg, then as a youth advisor in the City of Berlin from 1987. In 1986 she co-founded a group called Church Solidarity (Solidarische Kirche), which campaigned for greater democracy in the church and in society.[3] In 1988 she joined the Initiative for Peace and Human Rights, which formed part of the resistance to the Soviet-imposed communist regime in the 1980s.[4]