Have you read any of the letters of Pelagius? Individual excerpts and his protestations against charges of heresy do, prima facie, seem to exonerate him. He writes:
He wrote to pope Innocent, "We confess free will in such a sense that we declare ourselves to be always in need of the help of God"
But what does this mean to him? See I can quote Pelagius, and quote him quoting Augustine and paint him quite orthodox. That would be to ignore the fact that he fundamentally understood the terms differently
He states in his book De natura
The actual capacity of not sinning lies not so much in the power of will as in the necessity of nature. Whatever is placed in the necessity of nature undoubtedly appertains to the Author of nature, that is, God. How then can that be regarded as spoken without the grace of God which is shown to belong in an especial manner to God?
So of course God's assistance is involved, he created our nature! And again
Now, when it is said that the very ability is not at all of man's will, but of the Author of nature, - that is, God, -how can that possibly be understood to be without the grace of God which is deemed especially to belong to God? That this may become still plainer, we must enter on a somewhat fuller discussion of the point. Now we affirm that the possibility of anything lies not so much in the ability of a man's will as in the necessity of nature. Take for instance, my ability to speak. That I am able to speak is not my own; but that I do speak is my own, -that is, of my own will. And because the act of my speaking is my own, I have the power of alternative action, - that is to say, both to speak and to refrain from speaking. But because my ability to speak is not my own, that is, is not of my own determination and will, it is of necessity that I am always able to speak; and though I wished not to be able to speak, I am unable, nevertheless, to be unable to speak, unless perhaps I were to deprive myself of that member whereby the function of speaking is to be performed
And again, in his treatise on free will
We distinguish three things, arranging them in a certain graduated order. We put in the first place 'ability;' in the second, 'volition;' and in the third, 'actuality.' The 'ability' we place in our nature, the 'volition' in our will, and the 'actuality' in the effect. The first, that is, the 'ability,' properly belongs to God, who has bestowed it on His creature; the other two, that is, the 'volition' and the 'actuality,' must be referred to man, because they flow forth from the fountain of the will. For his willing, therefore, and doing a good work, the praise belongs to man; or rather both to man, and to God who has bestowed on him the 'capacity' for his will and work, and who evermore by the help of His grace assists even this capacity. That a man is able to will and effect any good work, comes from God alone. So that this one faculty can exist, even when the other two have no being; but these latter cannot exist without that former one. I am therefore free not to have either a good volition or action; but I am by no means able not to have the capacity of good. This capacity is inherent in me, whether I will or no; nor does nature at any time receive in this point freedom for itself. Now the meaning of all this will be rendered clearer by an example or two. That we are able to see with our eyes is not of us; but it is our own that we make a good or a bad use of our eyes. So again (that I may, by applying a general case in illustration, embrace all), that we are able to do, say, think, any good thing, comes from Him who has endowed us with this 'ability,' and who also assists this 'ability;' but that we really do a good thing, or speak a good word, or think a good thought, proceeds from our own selves, because we are also able to turn all these into evil. Accordingly,--and this is a point which needs frequent repetition, because of your calumniation of us,--whenever we say that a man can live without sin, we also give praise to God by our acknowledgment of the capacity which we have received from Him, who has bestowed such 'ability' upon us; and there is here no occasion for praising the human agent, since it is God's matter alone that is for the moment treated of; for the question is not about 'willing,' or 'effecting,' but
simply and solely about that which may possibly be.
He does indeed attribute praise to God, but it rests upon the nature He has created. Hence his first error in conflating the natural order and the supernatural. Second, he errs by affirming that God is behind only the ability and not the execution of the good act. Even if the Church teaching against him does not necessitate the belief in the intrinsic efficacy of grace (like Thomists and Augustinians hold), it does indeed require the belief that God's grace immediately cooperates and in fact (in the order of nature) precedes the act, not merely in granting the ability or faculty, but in the action itself.
Ignem veni mittere in terram, et quid volo nisi ut accendatur?.... Quid autem et a vobis ipsis non judicatis quod justum est?