"For the avoiding of diversities of opinions": John Henry Newman, ally of the radical Latitudinarians

In The Case of Arian Subscription Considered (1721), High Church theologian Daniel Waterland robustly refuted the notion proposed by Arians and Unitarians that the Articles of Religion were subscribed to only insofar as they were agreeable to Scripture.  This, Waterland contended, was a rejection of the very practice of subscription, a practice necessary to secure the traditional High Church virtues of unity and conformity:

To make it still plainer that such subscription is fraudulent; let it be considered what the ends and purposes intended by the ruling powers, in requiring subscription, are. They are expressed in our public laws and canons to this effect; that pastors may be sound in the faith, that no doctrines be publicly or privately taught but what the Church and State approve of; that all diversity of opinions, in respect of points determined, be avoided; that one uniform scheme of religion, one harmonious form of worship, (consonant to Scripture and primitive Christianity,) be constantly preserved among clergy and people. These are the main ends designed by subscription. But if subscribers may take the liberty of affixing their own sense to the public forms, in contradiction to the known sense of the imposers, all these ends are liable to be miserably defeated and frustrated. Pastors, instead of being sound in the faith, (which is but one,) may have as many different faiths as they happen to have different wits or inventions. Multiplicity of doctrines, opposite to each other, may be publicly taught and propagated: and, instead of any uniform scheme of religion, or form of worship, there may happen to be as many different and dissonant religions in the same church or kingdom, as there are pastors or parishes. These being the natural consequences of that latitude of subscription now pleaded for, it is evident that such a latitude is a contradiction to the very end and design of all subscription.

Regarding "the known sense of the imposers", Waterland is explicit that this is the authoritative reading of the Articles:

That the sense of the compilers and imposers (where certainly known) must be religiously observed; even though the words were capable of another sense ... That the sense of the compilers and imposers when certainly known, (as in the present case it is,) is to be religiously observed by every subscriber.

Against this background, we can see why the Old High Church tradition utterly rejected Tract XC.  Newman's reading of the Articles declared:

we have no duties toward their framers.

Referring to the framers of the Articles, he contrasts "their words" with "our meaning".  Also significantly, Newman insisted:

the Articles are evidently framed on the principle of leaving open large questions, on which the controversy hinges. They state broadly extreme truths, and are silent about their adjustment.

Waterland confronted a similar form of argument from the Arians and Unitarians:

What a fanciful representation is here of our public forms; as if they, either at first sight, or at all, looked towards Arianism; when the very strongest words which the wit of man can devise to exclude it occur everywhere in our public forms. And it is so far from being obscure whether the compilers and imposers intended to exclude it, and to profess the Catholic doctrine up to the height, that it is demonstration they did intend it. This plea therefore has nothing to rest upon but a misrepresentation of fact.

Tract XC, then, stands in continuity with earlier radical Latitudinarian attempts to deprive of meaning subscription to the Articles.  Exalting other preferred theological sources over the composers of the Articles - sources self-evidently rejected by the composers - and pleading a supposed obscurity in the Articles to justify theological positions clearly rejected by them, Tract XC achieved what the earlier radical Latitudinarians could not: in Waterland's words, "such a latitude is a contradiction to the very end and design of all subscription".

Waterland did hint that the Arian and Unitarian approach to subscription could lead to equally meaningless statements regarding the controversies of the Reformation:

In the same way, a man might subscribe to the decrees of the Council of Trent, or to every article of Pope Pius's Creed. 

The doctrinal incoherence sought by the radical Latitudinarians was delivered by Newman and Tract XC, with his deceptive insistence that the Articles could be read as concurring with the Council of Trent.  Against this, and as a response to that doctrinal incoherence which was Newman's departing gift to the Church of his birth, we might receive afresh the witness of the High Church tradition, the insistence of Waterland that subscription to the Articles is a means of centring Anglicanism around the deposit of Faith, "for the avoiding of diversities of opinions":

Subscribers must believe it true in that particular sense which the Church intended, (so far as that sense may be known,) for the Church can expect no less; the design being to preserve "one uniform tenor" of faith, to preclude " diversity of opinions," to have her own explications, and none other, (as to points determined,) taught and inculcated; and to tie men up from spreading or receiving doctrines contrary to the public determinations. These and the like ends cannot be at all answered by subscription, unless the subscriber give his assent to the Church's forms in the Church's sense; that is, in the sense of the compilers and imposers.