Synod, ministerium, unionism
What is the difference between a Synod and a Ministerium? What is meant by Unionism?
A ministerium is a group of ministers united for a common cause. They only—and not their congregations—would belong to the ministerium.
A synod describes congregations, with its called workers and laity, joined together and committed to a common calling.
Unionism refers to joint worship and religious work of people who are not united in doctrine.