The references to Pelagius interest me. Its obvious he annoyed the churchmen of his day; its hard to find his arguments in his own words, since we mostly know what he thought from his enemies.
Pelagius’ error consisted of ... a failure to recognize that right standing with God can only be imputed to us as the result of an external cause God’s grace)...
I think Pelagius' response was "yes, but you have it".
It used to be hard. Nowadays, you can find his own words for sale on Amazon. But since it isn't that hard, IMO the only people who continue to defend him are those who seek to rehabilitate a historically heretical theology.
Princeton theologian B. B. Warfield considered Pelagianism "the rehabilitation of that heathen view of the world," and concluded with characteristic clarity, "There are fundamentally only two doctrines of salvation: that salvation is from God, and that salvation is from ourselves. The former is the doctrine of common Christianity; the latter is the doctrine of universal heathenism."
-- from the thread Pelagianism: The Religion of Natural Man