Disagreements within the General Synod as to the binding character of the Lutheran Confessions caused a split, with the Illinois Synod joining with several other Lutheran synods to form the new General Council of the Evangelical Lutheran Church in North America in 1867.
[1] In 1871, the Illinois Synod withdrew from the General Council due to the issue of the Four Points regarding the permissible forms of association with non-Lutheran churches and organizations.
It then joined with other confessional Lutheran synods that either had withdrawn from the General Council or had declined to join it to establish the Evangelical Lutheran Synodical Conference of North America in 1872.
At some point the Illinois Synod expanded its name to the Evangelical Lutheran Synod of Illinois and Other States as congregations in Missouri joined it.
At the time of the merger, the Illinois Synod had 26 congregations, 23 pastors, and 6,004 communicant members.