"We do not stand in need of fuller notices": a Hackney Phalanx sermon for Trinity Sunday

From A Course of Sermons for the Festivals and Fasts of the Church of England (1821) by Joseph Holden Pott - associated with the Hackney Phalanx - a sermon for Trinity Sunday, with Ephesians 2:18 as the text.  

The sermon is an example of the Trinitarian orthodoxy which had prevailed against the 18th century anti-Trinitarians in the Church of England. It echoes Waterland's call for the doctrine of the Trinity to be proclaimed in its "native simplicity", a view also urged by Taylor.  This was a denial of the anti-Trinitarian charge that the Trinitarian teaching was a scholastic obfuscation of the Gospel.  The doctrinal and dogmatic language - while of importance in controversy - was secondary to the proclamation of the Trinity in Gospel and Scripture.

Pott points to his text as exemplifying how the doctrine of the Holy Trinity is "the sublimest doctrine which the sacred page of Scripture holds out for our acceptance and belief":

And first let it be well observed, that the text which so sufficiently reveals the doctrine which we hold, implies by the way in which the Father, Son, and Holy Spirit, are there introduced, their joint prerogative, and makes that discovery the very ground of access to the throne of Grace. Thus it presents to us at once the strongest reasons which could operate for revealing such particulars to those whose chief business it must be to make good their return to God. They should know in whom they believe; in whom they are to trust, and in a due degree, in what manner the great work of reconciliation and redemption is conducted and accomplished.

Does the main inference which has been drawn from the testimony of our Lord's Apostle, appear to be too strong, as arising from the bare mention of the joint influence and co-operation of the Father, Son, and Holy Spirit, in one work of redemption? Look, then, to the chief provision which was made by our Blessed Lord himself for that privilege of access which the text describes: look to the solemn form of dedication and reception to the Christian household. It contains the same enumeration of three several persons concurring in the same work of our redemption, of whom it is impossible to think, that if they were not one in nature and in glory, they could be so joined and enumerated in the draft which is thus given of the mode of access opened to us to the state of Grace, or that they could be so united in the form of faith into which men are baptized.

The Trinity, therefore, is not the product of theological speculation, but is at the heart of revelation.  What is more, denial of the Trinity results in instability and incoherence being introduced into the narrative of salvation proclaimed in the Scriptures:

It is far more difficult to understand in what way divine Power can be exercised, either by grant or delegation, by created beings; and that too in such high degrees as are manifestly incommunicable by Him who hath declared that he will not give his glory to another. How shall the Son and Holy Spirit be the sources of all Grace, and the dispensers of all succour, and yet not partakers of the fulness of the wellspring? How shall they employ an universal agency in this work; hear all prayers, and search all bosoms; heal all infirmities; redress all needs; receive all suits; watch over all, and intercede for all? How shall they be united unto all believers by spiritual ties of union and communication?

Rather than the Trinity claiming excessive knowledge of God, it is denial of the Trinity - revealed in holy Scripture - which claims to know more than revelation:

that as we must believe on testimonies which are built upon sufficient evidence, that the Son, and Holy Spirit do partake one common nature with the Father, without division in the Godhead, so is it impossible for any man to shew, that such participation cannot be. It involves no contradiction. It affirms only concerning the divine nature more than could be gathered by us or collected, except it were disclosed by revelation. The truth of what is so revealed we are unable to disprove, unless we will take upon us to know what we must be sensible we cannot know, even all the depths, and all the mysteries of God's adorable Perfections, and the qualities of his transcendent Essence. That no contradiction is involved in those distinctions, and in that participation, which have here been touched, has been often urged, and proved too, by solid arguments. It has been shewn as frequently, that the distinctions which are applicable to the mutual relation, and the manner of subsistence, between those by whom our access to the throne of Grace is made good, does not destroy the bond of unity.

There is also a "propriety" to the sufficiency of revelation, allowing us to behold the Holy Trinity insofar as is necessary for salvation, but not beyond:

Thus having shewn with what propriety such revelations have been made to us; and for what apparent reasons it hath pleased God to disclose to us so much of the nature of the Godhead; we have only to consider why such revelations were not rendered more explicit. There is no necessity to dwell long on this particular, for if we have found that so much is revealed as was needful to make us, understand in whom we have believed; and how our access to the Father, by the Son, and through the Holy Spirit, is conducted and made good, they must be bold indeed who shall require that more should be discovered either to gratify a curious spirit, or to remove the scruples of a dubious mind. To those, however, whose enquiry may be modest and becoming, we may offer some remarks on this head also. Can it, then, seem wonderful to considerate men, that what belongs to the nature and the essence of the Godhead, should transcend our perfect comprehension, although it be revealed in part? Can we fail to see that the reason why it is not unfolded and explained more fully to us, may be this, that we do not stand in need of fuller notices than may serve the ends of faith; and that it seems also more than probable that we want the faculties at present to conceive such thing's more perfectly?

... It is enough, then, that the word of revelation, which, together with the light of reason, declares indisputably that the Godhead is but one and undivided, the same Word ascribes also the divine prerogatives to the Son, and Holy Spirit, by whom we have access to the Father: and this leads us to conclude, that there are three Persons in that one undivided Godhead. 

Pott's sermon gives a good insight into why the early- and mid-18th century anti-Trinitarian assault failed. Such Orthodox preaching demonstrated how the Trinity cohered with the Scriptural narrative of redemption; how the doctrine of the Trinity was inherent to the Christian confession; and how anti-Trinitarians were seeking to radically re-order Christian belief through claiming to have greater insight into the Godhead than revelation permitted.