With the Logos set of Wesley’s complete works, I can easily scan for those nasty topics like Pelagius.
Here are two areas I have found.
Yea, I would not affirm, that the arch-heretic of the fifth century, (as plentifully as he has been bespattered for many ages,) was not one of the holiest men of that age, not excepting St. Augustine himself…I verily believe, the real heresy of Pelagius was neither more nor less than this: The holding that Christians may, by the grace of God, (not without it; that I take to be a mere slander,) “go on to perfection;” or, in other words, “fulfil the law of Christ.”
“But St. Augustine says:”—When Augustine’s passions were heated, his word is not worth a rush. And here is the secret: St. Augustine was angry at Pelagius: Hence he slandered and abused him, (as his manner was,) without either fear or shame. And St. Augustine was then in the Christian world, what Aristotle was afterwards: There needed no other proof of any assertion, than Ipse dixit: “St. Augustine said it.” – Sermon 68
Wesley was accused of semi-Pelagianism. He responded,
I know no creature (of us) who says, “Part of our salvation belongs to Christ, and part to us.” No; we all say, Christ alone saves us from all sin; and your question is not about the Author, but the measure, of salvation. Both agree, it is all Christ; but is it all salvation, or only half salvation, he will give? Who was Pelagius? By all I can pick up from ancient authors, I guess he was both a wise and a holy man. But we know nothing but his name; for his writings are all destroyed; not one line of them left. – Letter to a Mr. Coates, 1761
I note that the first one is part of the doctrinal standards of the United Methodist Church.
By the way, Fr. John was likewise a fan of Montanus. He saw in both men his own doctrine of “going on to perfection.”