Below is a quotation from St. Bernard of Clairvaux on what was, back then, the novel idea of the Immaculate Conception. He was 12th century and considered this a new, and disastrous, idea. Thus, his language is very strong. Nevertheless, this helps to verify two things. One, this was a doctrine that started to become popular after the Great Schism, and two that this does indeed qualify as a novel doctrine.
“I am frightened now, seeing that certain of you have desired to change the condition of important matters, introducing a new festival unknown to the Church, unapproved by reason, unjustified by ancient tradition. Are we really more learned and more pious than our fathers? You will say, ‘One must glorify the Mother of God as much as Possible.’ This is true; but the glorification given to the Queen of Heaven demands discernment. This Royal Virgin does not have need of false glorifications, possessing as She does true crowns of glory and signs of dignity.
Glorify the purity of Her flesh and the sanctity of Her life. Marvel at the abundance of the gifts of this Virgin; venerate Her Divine Son; exalt Her Who conceived without knowing concupiscence and gave birth without knowing pain. But what does one yet need to add to these dignities? People say that one must revere the conception which preceded the glorious birth-giving; for if the conception had not preceded, the birth-giving also would not have been glorious. But what would one say if anyone for the same reason should demand the same kind of veneration of the father and mother of Holy Mary? One might equally demand the same for Her grandparents and great-grandparents, to infinity.
Moreover, how can there not be sin in the place where there was concupiscence? All the more, let one not say that the Holy Virgin was conceived of the Holy Spirit and not of man. I say decisively that the Holy Spirit descended upon Her, but not that He came with Her…I say that the Virgin Mary could not be sanctified before Her conception, inasmuch as She did not exist. if, all the more, She could not be sanctified in the moment of Her conception by reason of the sin which is inseparable from conception, then it remains to believe that She was sanctified after She was conceived in the womb of Her mother.
This sanctification, if it annihilates sin, makes holy Her birth, but not Her conception. No one is given the right to be conceived in sanctity; only the Lord Christ was conceived of the Holy Spirit, and He alone is holy from His very conception. Excluding Him, it is to all the descendants of Adam that must be referred that which one of them says of himself, both out of a feeling of humility and in acknowledgement of the truth: Behold I was conceived in iniquities (Ps. 50:7). How can one demand that this conception be holy, when it was not the work of the Holy Spirit, not to mention that it came from concupiscence? The Holy Virgin, of course, rejects that glory which, evidently, glorifies sin. She cannot in any way justify a novelty invented in spite of the teaching of the Church, a novelty which is the mother of imprudence, the sister of unbelief, and the daughter of lightmindedness”