The grace and charity towards his opponents was always a mark of Channing’s personality. Here are a few excerpts I’ve made of a letter penned by Channing in response to a really vitriolic attack on what he stood for, and the people who stood with him - his congregation and related ones. The restraint he shows is, I think, a good example; and his defense is remarkably put forth. He touches on a couple of doctrinal issues as a response to the distortions of a certain well-read periodical, but also expresses his understanding of church. You’ll see what I mean. I find this to be uplifting of a Sunday morning!
From the letter:
We both agreed in our late conference, that a majority of our brethren believe, that Jesus Christ is more than man, that he existed before the world, that he literally came from heaven to save our race, that he sustains other offices than those of a teacher and witness to the truth, and that he still acts for our benefit, and is our intercessor with the Father.
It is indeed true, as Mr. Wells says, that we seldom or never introduce the Trinitarian controversy into our pulpits. We are accustomed to speak of the Father as God, and of Jesus Christ as his son, as a distinct being from him, as dependent on him, subordinate to him, and deriving all from him. This phraseology pervades all our prayers, and all our preaching. We seldom or never, however, refer to any different sentiments, embraced by other christians, on the nature of God or of Jesus Christ. … We have aimed at making no false impression. We have only followed a general system, which we are persuaded to be  best for our people and for the cause of christianity; the system of excluding controversy as much as possible from our pulpits. In compliance with this system, I have never assailed Trinitarianism; nor have I ever said one word against Methodism, Quakerism, Episcopalianism, or the denomination of Baptists; and I may add Popery, if I except a few occasional remarks on the intolerance of that system. The name of sects, with that single exception, has never passed my lips in preaching, through my whole ministry, which has continued above twelve years. We all of us think it best to preach the truth, or what we esteem to be the truth, and to say very little about errour, unless it be errour of a strictly practical nature. Our method is, to state what we conceive to be more honourable, and ennobling, and encouraging views of God’s character and government, and to leave these to have their effect, without holding up other christians to censure or contempt. We could, if we were to make strenuous efforts, render the  name of Calvinist as much a word of reproach in our societies, as that of Unitarian is in some parts of our country. But we esteem it a solemn duty to disarm instead of exciting the bad passions of our people. We wish to promote among them a spirit of universal charity. We wish to make them condemn their own bad practices, rather than the erroneous speculations of their neighbor. We love them too sincerely to imbue them with the spirit of controversy.
We have seldom or never assailed the scheme of the Trinity, not only from our dislike to controversy in general, but from a persuasion that this discussion would, above all others, perplex and needlessly perplex a common congregation, consisting of persons of all ages, capacities, degrees of improvement, and conditions in society .…Many of us have been disinclined, not only to assail systems which we do not believe, but even to enforce the views which we have given of the rank and character of Jesus Christ; because we have known, how divided the best men have been on these topicks, and how largely we ourselves partake of the fallibility of our nature; because we have wished, that our hearers should derive their impressions on these points as much as possible from the scriptures; and because we have all been persuaded, that precision of views upon these subjects is in no degree essential to the faith of practice of a christian. --we have considered the introduction of the Trinitarian controversy into the pulpit, as the less necessary, because we have generally found that common christians admit that distinction between God and his Son, and that subordination of the Son, which we believe to be the truth; and as to that very small part of our hearers, who are strongly attached to the doctrine of the Trinity, while we have not wished to conceal from them our difference of opinion, we have been fully satisfied, that the most effectual method of promoting their holiness and salvation was to urge on them perpetually those great truths and precepts, about which there is little contention, and which have an immediate bearing on the temper and the life.
Accustomed as we are to see genuine piety in all classes of christians, in Trinitarians and Unitarians, in Calvinists and Arminians, in Episcopalians, Methodists, Baptists, and Congregationalists, and delighting in this character wherever it appears, we are little anxious to bring men over to our peculiar opinions. . Our great and constant object has been to promote the spirit of Christ, and we have been persuaded, that in this way we should most effectually promote the interests of christian truth.
On the present occasion, when our moral character is impeached, we are justified, I think, in an appeal to our respective societies; and I trust, my friend, that we are our accused brethren can say with confidence to those to whom we minister, “Brethren, you know us, for we live among you; we visit you in your families, we speak to you from the pulpit; we repair to you in your sorrows, and we sit too at the table of your festivity. You know something of our conduct in our families, and in the common relations of life. We are, indeed sensible, that in all these situations, we have exhibited to you much of human imperfection, and our frequent prayer to God is, that he will forgive our deficiencies. But, brethren, we ask you to recollect our general deportment and ministrations. Have we seemed to you men of artifice and deceit, men without reverence for truth, and without the fear of God, men of sordid and selfish views, seeking your wealth or applause, and careless of your souls? Have we ever seemed to you to be  labouring to build to cause, or to establish a party, which we were ashamed to acknowledge? Have we ever directed you to any foundation of hope or guide of life, but the Gospel of Christ? Have we not continually exhorted you, as a father doth his children, that you would walk worthy of this religion from heaven? In your affliction have we not supplied you with the consolations which it offers? and in the more dangerous seasons of enjoyment, have we not discovered the purity and moderation which it inculcates? To what work of christian usefulness have you found us reluctant? In what relation of life have you found us unfaithful? On what occasion have we discovered, that our profession is a cloak of hypocrisy? It is not our design, by these questions, to advance our own glory; God forbid it: But we wish to impress you deeply with the criminality of those aspersions, which are cast habitually on your teachers; and with the urgent necessity of discouraging that unrelenting party spirit, which has no respect for innocence or virtue, and which threatens to overwhelm our churches with discord and contention.”
Excerpted from: A LETTER TO THE REV. SAMUEL C. THACHER ON THE ASPERSIONS CONTAINED IN A LATE NUMBER OF THE PANOPLIST, ON THE MINISTERS OF BOSTON AND THE VICINITY.
BY WILLIAM E. CHANNING, Minister of the Church of Christ in Federal Street, Boston 1815
The full letter - a lot longer, here: http://www.americanunitarian.org/lettertothacher.htm