Some fragments on Scripture and subordinate standards:
Scripture is the norma normans (the norming norm, the rule that rules)
Confessions are the norma normata (a norm that is normed/a rule that is ruled)
Christian faith begins with a confession of faith by the individual (e.g. Rom. 10:9) and the reception of confessed truths by the Christian community (e.g. 1 Cor. 15:1-3)
A Confession of faith is not an arbitrary, unnatural, or purely cerebral artefact, that is somehow foreign to normal Christian life and experience, but (as the texts above indicate) belongs to the very essence of Christian existence
A Confession is a corporate ecclesiastical statement of Christian belief and practice
A Confession of faith is a verbal affirmation of truth and implicitly, or explicitly, a verbal denial of error
A Confession is composed out of biblical and extra biblical language, the latter out of necessity in order to distinguish orthodox appeals to the teachings of Scripture from heterodox ones
A Confession is a subordinate standard
As a subordinate standard a Confession is derived in whole and in part from Scripture
A Confession is accepted as authoritative insofar as it is in agreement with Scripture and faithfully represents the content of what the Scriptures teach
When the teaching of a particular Confession is denied, by an appeal to Scripture, a new Confession (personal or corporate, written or unwritten) has been posited in place of the old one (in part or in whole)
It is impossible to be Non-Confessional, even if a church body, or network of churches, has an aversion to written Confessions
Without a written, or unwritten, no fellowship, unity, or co-operation is possible within or between churches
Confessions can be maximal (think Westminster Confession) or minimal (think Apostles' Creed or parachurch statements of faith)
Minimal confessions are implicitly maximal is their exposition as they rely on more comprehensive statements and definitions to clarify, explain, define and defend their brief propositions
And to round off, here is a helpful and thought provoking comment by R. A. Finlayson:
A Confession is referred to as a Church's 'subordinate standard' because it is in very fact subordinate to the Scriptures, the fountainhead of all revealed truth. This subordination, however, does not affect its authority in matters of faith, but rather serves to emphasise the fact that it is derived from Scripture."The Significance of the Westminster Confession" in Reformed Theological Writings, p. 231-2
When a Confession is accepted, therefore, it is accepted as in accordance with the truth of Scripture, and we profess that we have examined both the Scripture and the Confession and that we have found them in agreement.
For that reason we cannot appeal from the Confession to Scripture in a way of repudiating the Confession, without thereby withdrawing our subscription to it as agreeable to the Scripture and the Confession of our Faith.
To set aside its doctrine in favour of some other interpretation of Scripture is manifestly to abandon the Confession altogether.