Last post I presented evidence of Ben Franklin calling Unitarian minister Theophilus Lindsey "honest." Franklin also described Joseph Priestley that way.
As Franklin wrote to to Benjamin Vaughn in 1788:
"Remember me affectionately...to the honest heretic Dr. Priestley. I do not call him honest by way of distinction, for I think all the heretics I have known have been virtuous men. They have the virtue of Fortitude, or they would not venture to own their heresy; and they cannot afford to be deficient in any of the other virtues, as that would give advantage to their many enemies...Do not however mistake me. It is not to my good friend's heresy that I impute his honesty. On the contrary 'tis his honesty that has brought upon him the character of heretic."
Here are primary sources where you can view the quotation in context.