Peter Brown has written excellently on Augustine's "invention" of Pelagianism. Though Morgan (Pelagius) seems not to have been an exceptionally humble guy, what little we know of his actual theologizing does not seem novel from Eastern perspectives because in such perspectives, even creation is grace--gift, so it is not so much that Morgan made G-d nearly unnecessary as that G-d is so at the heart of all things that there is no place finally without G-d's grace, so act from that place--the place of creation completed.
I don't think there's anything wrong with seeing creation as grace, but the point is that it is not sufficient grace. If you get all the grace you need from the creation of the Father and the immanence of the Spirit, there isn't much left for Jesus to do. I don't know if that was what Pelagius preached, but that was one of the complaints against him. Also, I think that "God in all things" really needs to be contextualized in the Eastern Christian habit of seeing the material world through the lens of mystical revelation -- eating intimates the heavenly feast, sex prefigures divine union, etc. Westerners have a habit of studying the physical world on its own terms and trying to discern philosophical norms from it, which is how we wound up with Social Darwinism and similar horrors.
Meanwhile, Quotemeister Neil submitted an excerpt from Orthodox theologian John Meyendorff:
It has been often recognized that Eastern patristic thought ignores the notion of a transmission of guilt from Adam to his descendants. However, it does not ignore the very fact of cosmic fallenness. This fallenness is not expressed in terms of divine punishment inflicted upon all humans (the Augustinian massa damnata) from parents to children, but rather in terms of a usurpation or illegitimate tyranny exercised by Satan upon God's creation. Humans are rather seen as victims of the universal reign of death (indeed Satan is a 'murderer from the beginning': Jn 8.44). 'Through fear of death, they are subject to lifelong bondage' (Heb 2.15). What is being transmitted from parents to children is not sin but mortality and slavery, creating a condition where sin is inevitable: 'Having become mortal,' writes Theodoret of Cyrus, '[Adam and Eve] conceived mortal children, and mortal beings are necessarily subject to passions and fears, to pleasures and sorrows, to anger and hatred.' The model here is Darwinian: fear of death generates struggle for survival, and survival is attainable only at the expense of others - a survival of the fittest, winning over the weak. 'By becoming mortal, we acquired greater urge to sin,' writes Theodore of Mopsuestia, 'because we depend on food, drink, and other needs, and the desire to acquire those leads inevitably to sinful passions.' Patristic references can be easily mutiplied, and their context is understandable if one remembers that the Greek Fathers read the Greek original of the famous passage of Rom 5.12 ('As sin came into the world through one man and death through sin, and so death spread to all men, because [or 'and because of death'] all have sinned') and were not conditioned by the Latin mistranslation, which implied that all sinned 'in Adam.'
It reminds me, though, of a quote Bill Allison posted just today:
Without death there is little innovation. Extinction -- death of a species -- is part and parcel of evolutionary change. In the absence of this kind of extinction new developments would not prosper.