Regarding the latter assertion, I noted Franklin's letter to John Calder (one that denies certain parts of the Bible as divinely inspired) where in 1784 he wrote:
By the way how goes on the Unitarian Church in Essex Street? and the honest Minister of it, is he comfortably supported?That "honest Minister" was none other than the legendary Theophilus Lindsey.
What about the "gentle proselytizing"? In 1774, when Lindsey started the Unitarian Church in Essex Street, Franklin enclosed, in a letter to an orthodox Christian correspondent, Lindsey's "The Book of Common Prayer Reformed According to the Plan of the Late Dr. Samuel Clarke …[,] the new liturgy that Lindsey devised for his Unitarian congregation in London...."
To which the orthodox Thomas Coombe replied:
Mr. Lindsey’s production was a curiosity that I had for some time been wishing to see. I had heard of his fame, but knew nothing of his particularities, till I saw his book, which appears to me to be the weak effort of a discontented and disordered mind. Dr. Clarke, you remember, proposed some alterations in our Common-Prayer Book; but the dreadful elisions which Lindsey has made, shew that he disapproves of the spirit of the whole.1In short, the gentle proselytizing failed.