Over at Pyromaniacs there has been some discussion about the book Listening to the Beliefs of the Emerging Churches, and particularly Dan Kimball's contribution.
Below I have posted Jaroslav Pelikan's discussion of the trinitarian orthodoxy of some of the Pelagians and the sticking point for their position in the Nicene Creed. To begin with here is Pelikan's summary of the the doctrine of sin held by Celestius:
"Adam was created mortal and would have died whether he had sinned or not sinned; the sin of Adam injured only him, not the human race; the law leads to the kingdom [of heaven], just as the gospel does; even before the coming of Christ there were men without sin; newborn infants are in the same state which Adam was before his transgression; the whole human race does not die through the death and transgression of Adam, nor does it rise again through the resurrection of Christ."
Following this Pelikan comments:
Much of this could claim support from the tradition as well as from contemporary Eastern theologians. What is more, it was combined with an impeccable trinitarian orthodoxy. Pelagius confessed: "I believe in the Trinity of the one substance, and I hold all things in accordance with the teachings of the holy catholic church." Before the outbreak of the controversy on grace and sin he had written a treatise On the Faith of the Trinity. Pelagius had a reputation for teaching "the right faith." Celestius, too, could wholeheartedly recite the creed, "from the Trinity of the one Godhead all the way to the kind of resurrection of the dead that there is to be." If the touchstone of orthodoxy was adherence to the true faith concerning the Trinity and the person of Christ, it was incorrect to call this doctrine of sin and grace a "heresy." Those who held to erroneous doctrines in this area were to be anathematized "as fools, not as heretics, for there is no dogma."
But this assessment of the controversy was not to last, as Pelikan further notes:
But the standard of trinitarian orthodoxy, the Nicene Creed, also contained the statement: "We confess...one baptism for the forgiveness of sins." And by the first part of the fifth century this meant, as a rule, the baptism of infants.
And the Pelagians held to doctrines that were inconsistent with this understanding of the need for forgiveness, original sin, and the subsequent necessity of infant baptism. Pelikan finally observes that:
In the person of Celestius, Pelagianism was condemned by the Council of Ephesus in 431 as a heresy.
Now the point of all this is to show that the Nicene Creed was an insufficient test to deal with the issues of sin and grace in salvation. It did, to be sure, not leave those issues completely untouched. But even when it touched upon them it did not clarify the crucial relationship of grace and faith. In fact we should go further and say with Warfield that "the problem which Augustine bequeathed to the Church for solution, the Church required a thousand years to solve," since it was "Augustine who gave us the Reformation."
For a fuller discussion of these matters see Pelikan, The Christian Tradition volume 1: The Emergence of the Catholic Tradition (100-600), and B. B. Warfield, "Augustine and the Pelagian Controversy," in The Works of Benjamin B. Warfield vol. IV: Studies in Tertullian and Augustine