1) Pelagius and Celestius used Mary, the mother of Jesus, as an example of one born free of original sin. Vincent of Lerins points out the origin of the teaching of the immaculate conception with these words: "Who ever originated a heresy that did not first dissever himself from the consentient agreement of the universality and antiquity of the Catholic Church? That this is so is demonstrated in the clearest way by examples. For who ever before the profane Pelagius attributed so much antecedent strength to Free-will, as to deny the necessity of God's grace to aid it towards every good in every single act? Who ever before his monstrous disciple Celestius denied that the whole human race is involved in the guilt of Adam's sin?"
Philip Schaff, Nicene and Post-Nicene Fathers (Grand Rapids: Eerdmans, 1955), Volume XI, Vincent of Lerins, A Commonitory 24.2, pp. 149-150
2) The Roman Catholic patristic scholar, Walter Burghardt, confirms the patristic and papal rejection of this doctrine historically: 'Post-Augustinian patristic thought on the perfection of Mary reveals two conflicting currents. There is a negative, unfavorable trend rooted in Augustine's anti-Pelagianism; it accentuates the universality of original sin and articulates the connection between inherited sin and any conception consequent upon sinful concupiscence. The root idea is summed up by Leo the Great: 'Alone therefore among the sons of men the Lord Jesus was born innocent, because alone conceived without pollution of carnal concupiscence.' The same concept is discoverable in St. Fulgentius, Bishop of Ruspe in Africa (d. 533), the most significant theologian of his time; in Pope Gregory the Great (d. 604) at the end of the sixth century; and a century later in Venerable Bede, a scholar renowned throughout England' (Juniper Carol, Ed., Mariology (Milwaukee: Bruce, 1955), Volume One, p. 146).
3) "For all have sinned and fall short of the glory of God" - Romans 3:23
4) "There is none righteous, not even one" - Romans 3:10
"Not even one."
That is an interesting point. Of course, in them using this point to advance their heresy, implicit is the fact that this was widely accepted prior to their attempt...else it would make no sense for them to use it in the first place.
It's interesting that you would cite Vincent of Lerins. Here's what he actually wrote:
“Shun profane novelties of words,” which to receive and follow was never the part of Catholics; of heretics always was. In sooth, what heresy ever burst forth save under a definite name, at a definite place, at a definite time? Who ever originated a heresy that did not first dissever himself from the consentient agreement of the universality and antiquity of the Catholic Church? That this is so is demonstrated in the clearest way by examples. For who ever before that profane Pelagius attributed so much antecedent strength to Free-will, as to deny the necessity of God’s grace to aid it towards good in every 150single act? Who ever before his monstrous disciple Cœlestius denied that the whole human race is involved in the guilt of Adam’s sin? Who ever before sacrilegious Arius dared to rend asunder the unity of the Trinity? Who before impious Sabellius was so audacious as to confound the Trinity of the Unity? Who before cruellest Novatian represented God as cruel in that He had rather the wicked should die than that he should be converted and live? Who before Simon Magus, who was smitten by the apostle’s rebuke, and from whom that ancient sink of every thing vile has flowed by a secret continuous succession even to Priscillian of our own time,—who, I say, before this Simon Magus, dared to say that God, the Creator, is the author of evil, that is, of our wickednesses, impieties, flagitiousnesses, inasmuch as he asserts that He created with His own hands a human nature of such a description, that of its own motion, and by the impulse of its necessity-constrained will, it can do nothing else, can will nothing else, but sin, seeing that tossed to and fro, and set on fire by the furies of all sorts of vices, it is hurried away by unquenchable lust into the utmost extremes of baseness?
A few pages later, he wrote:
[64.] Here, possibly, some one may ask, Do heretics also appeal to Scripture? They do indeed, and with a vengeance; for you may see them scamper through every single book of Holy Scripture,—through the books of Moses, the books of Kings, the Psalms, the Epistles, the Gospels, the Prophets. Whether among their own people, or among strangers, in private or in public, in speaking or in writing, at convivial meetings, or in the streets, hardly ever do they bring forward anything of their own which they do not endeavour to shelter under words of Scripture. Read the works of Paul of Samosata, of Priscillian, of Eunomius, of Jovinian, and the rest of those pests, and you will see an infinite heap of instances, hardly a single page, which does not bristle with plausible quotations from the New Testament or the Old.[65.] But the more secretly they conceal themselves under shelter of the Divine Law, so much the more are they to be feared and guarded against. For they know that the evil stench of their doctrine will hardly find acceptance with any one if it be exhaled pure and simple. They sprinkle it over, therefore, with the perfume of heavenly language, in order that one who would be ready to despise human error, may hesitate to condemn divine words. They do, in fact, what nurses do when they would prepare some bitter draught for children; they smear the edge of the cup all round with honey, that the unsuspecting child, having first tasted the sweet, may have no fear of the bitter. So too do these act, who disguise poisonous herbs and noxious juices under the names of medicines, so that no one almost, when he reads the label, suspects the poison.
Now, you mention St. Augustine. Let's take a little look at some of what he wrote:
We must except the holy Virgin Mary, concerning whom I wish to raise no question when it touches the subject of sins, out of honour to the Lord; for from Him we know what abundance of grace for overcoming sin in every particular was conferred upon her who had the merit to conceive and bear Him who undoubtedly had no sin. Well, then, if, with this exception of the Virgin, we could only assemble together all the forementioned holy men and women, and ask them whether they lived without sin while they were in this life, what can we suppose would be their answer? Would it be in the language of our author, or in the words of the Apostle John? I put it to you, whether, on having such a question submitted to them, however excellent might have been their sanctity in this body, they would not have exclaimed with one voice: If we say we have no sin, we deceive ourselves, and the truth is not in us? But perhaps this their answer would have been more humble than true! Well, but our author has already determined, and rightly determined, not to place the praise of humility on the side of falsehood. If, therefore, they spoke the truth in giving such an answer, they would have sin, and since they humbly acknowledged it, the truth would be in them; but if they lied in their answer, they would still have sin, because the truth would not be in them.
On Nature and Grace, 42
He only was born without sin whom a virgin conceived without the embrace of a husband,—not by the concupiscence of the flesh, but by the chaste submission of her mind. She alone was able to give birth to One who should heal our wound, who brought forth the germ of a pure offspring without the wound of sin. (emphasis mine)
The Good of Marriage; Four Different Cases of the Good and the Evil Use of Matrimony
You also cite Pope St. Leo the Great. It is really late and so I don't have the energy to dig too much up from him. One thing that is repeated in his sermons and letters is the perpetual virginity of Mary, including after giving birth to Christ:
Therefore, when the time came, dearly beloved, which had been fore-ordained for men’s redemption, there enters these lower parts of the world, the Son of God, descending from His heavenly throne and yet not quitting His Father’s glory, begotten in a new order, by a new nativity. In a new order, because being invisible in His own nature He became visible in ours, and He whom nothing could contain, was content to be contained: abiding before all time He began to be in time: the Lord of all things, He obscured His immeasurable majesty and took on Him the form of a servant: being God, that cannot suffer, He did not disdain to be man that can, and immortal as He is, to subject Himself to the laws of death. And by a new nativity He was begotten, conceived by a Virgin, born of a Virgin, without paternal desire, without injury to the mother’s chastity: because such a birth as knew no taint of human flesh, became One who was to be the Saviour of men, while it possessed in itself the nature of human substance. For when God was born in the flesh, God Himself was the Father, as the archangel witnessed to the Blessed Virgin Mary: “because the Holy Spirit shall come upon thee, and the power of the most High shall overshadow thee: and therefore, that which shall be born of thee shall be called holy, the Son of God.” The origin is different but the nature like: not by intercourse with man but by the power of God was it brought about: for a Virgin conceived, a Virgin bare, and a Virgin she remained. Consider here not the condition of her that bare but the will of Him that was born; for He was born Man as He willed and was able. If you inquire into the truth of His nature, you must acknowledge the matter to be human: if you search for the mode of His birth, you must confess the power to be of God. For the Lord Jesus Christ came to do away with not to endure our pollutions: not to succumb to our faults but to heal them. He came that He might cure every weakness of our corruptness and all the sores of our defiled souls: for which reason it behoved Him to be born by a new order, who brought to men’s bodies the new gift of unsullied purity. For the uncorrupt nature of Him that was born had to guard the primal virginity of the Mother, and the infused power of the Divine Spirit had to preserve in spotlessness and holiness that sanctuary which He had chosen for Himself: that Spirit (I say) who had determined to raise the fallen, to restore the broken, and by overcoming the allurements of the flesh to bestow on us in abundant measure the power of chastity: in order that the virginity which in others cannot be retained in child-bearing, might be attained by them at their second birth.
Letter 28, to Flavian.
One thing that you will see in the earlier Church fathers (the pre-Nicene variety) is a reference to Mary's perpetual virginity. Another thing is a reference to "no pain" in childbirth. If it matters, I will try to dig out a few of those references; however, the point is that Eve and her descendants were promised "pain" in childbirth...as a result of her disobedience to God (Gen 3:16).
Thanks for bringing up the Church Fathers on this thread!
About your four sources:
1. There’s an illogical assertion that suggests that since Pelagius inferred an incorrect conclusion from the docrtine of the sinlessness of Mary, that the doctrine itself is false. In fact, Augustine’s refutation of Pelagius also presumes the sinlessness of Mary.
2. I don’t know Walter Burghardt, so his opinion doesn’t mean much to me; the modern world is unfortunately full of CINO heretics. I don’t presume he is one, only that I don’t consider him a reliable source of faithful Catholic scholarship. I can’t even tell if he agrees with your assertion. I do know that his quote of St. Leo’s is quite plain to exclude Mary from its scope. For although “Men,” in many contexts includes women, “the sons of Men” is a construction which intentionally excludes women.
3. & 4. These verses are both part of the same passage, which was addressed in the original article. Both are citing prophecies from the Old Testament time to assert that Jews aren’t innately superior to Gentiles. Mary’s sinlessness neither negates the original assertion of the prophet (that he could find no righteous Jews), or St. Paul’s current assertion (that Jews were every bit as corrupt as Gentiles).
"Not even one."
That verse is a citation from Psalm 14. Better go back and read it in context, the way Paul understood it, because when you do, all the errors of the reformation come crashing down.