Honesty
The persons subscribing to that creed are bound to adhere to its teachings as long as they enjoy the privileges accruing from that subscription and from the fellowship it entails. They must relinquish these privileges whenever they are no longer able to avow the tenets expressed in the creed. In this sense a creed may be said to be normative within the communion adopting it. For the Church concerned officially declares in the creed what it believes the teaching of Scripture to be. And so the person who has come to renounce the tenets of the creed to which he once subscribed has no right to continue to exercise the privileges contingent upon subscription. He may not in such a case protest his right to these privileges by appeal to Scripture as the supreme authority. It is entirely conceivable that the creed may be in error and his renunciation of it warranted and required by Scripture. But his resort in such a case must be to renounce subscription and with such renunciation the privileges incident to it. Then he may proceed to expose the falsity of the creedal position in the light of Scripture.
John Murray, Tradition Romish and Protestant, The Collected Writings of John Murray, V4 (Edinburgh: Banner of Truth Trust, 1982), 272