Book 4 of 4 - External Means by which God Invites Us into the Society of Christ and Holds Us Therein
Chapter 9 - Councils and Their Authority
8-11 - Councils have deteriorated; even Nicea defective
8. This doesn't mean councils have no authority. One "may have its weight and be like a provisional judgment" subordinate to Scripture. It is not as if "every man has the right to accept or reject what the councils decide. Not at all!" The first four councils, from Nicea to Chalcedon were "pure and genuine," but "as affairs usually tend to get worse," recent ones have deteriorated.
9. Councils contradict each other. Constantinople forbade worship through images; Nicea later endorsed it. Ephesus II endorsed the Eutychean heresy; Chalcedon denounced it. We have to judge these by Scripture.
10. Nicea upheld "the chief article of our faith:" Christ's full incarnation and Deity, against Arius. But even the orthodox at Nicea were filled with other errors and intemperate dissension. Councils can certainly err.
11. Leo said Chalcedon was rash; Rome backtracks: councils are only infallible only in matters of salvation. But then they still claim we are bound to agree with all they say. The Spirit left enough error in councils, "lest we should put too much confidence in men."