Independent Social Democratic Party of Germany
He was also engaged in many communist organisations, joining the Independent Social Democratic Party of Germany in 1917, then went over to the Spartacist League in 1918 from which emerged the Communist Party of Germany (KPD). In 1920 he left the KPD, disappointed with the failure of the German Revolution, and embraced religion. In 1923, he returned to the KPD and very actively worked within the party.