Most of what's in Mariology was never taught for centuries. Gospel verses about Mary do not teach most what's contained in Mariology, but are rather applied to the teaching of Mariology.
Mariology firstly is the subset of theology pertaining to the Theotokos. Secondly, tnat is historically inaccurate. We have no evidence of any conflict over any doctrines pertaining to the Theotokos until the late fourth century, when St. Epiphanios documented the small schismatic groups known as the Collyridians and Antidicomarians; the former worshipped the Theotokos as a goddess, like the heretical Palmerians of the present, and the latter took the view that is unfortunately common among many Restorationist, Evangelical, Non Denominational and Radical Reformation churches which denied that which had been affirmed by all early Church Fathers who commented on the matter, and also the leading Protestant figures, namely, the perpetual virginity of the Blessed Virgin Mary and her status, contra Nestorius, as the Mother of God - doctrines upheld not just by Martin Luther, Thomas Cranmer and John Wesley, but also John Calvin, who reluctantly conceded the title Theotokos was correct and who never disputed the perpetual virginity of the Theotokos.
Additionally we have second century icons of the Theotokos, third century manuscript attestation of intercessory prayer to her (the specific prayer being one in continual use among the Orthodox), second century attestation of the beliefs of the Orthodox, Roman Catholics and high church Anglicans and some Lutherans concerning the nativity of tne Theotokos (although it is not canonical, but rather appears to parrot the ancient liturgies, the Protoevangelion of James), and likewise similar dating concerning the Theotokos.
No major Christian bishop objected to the veneration of the Blessed Virgin Mary until Nestorius, and his actions caused the first on-going schism in Christianity, the complex schism between the Church of the East (which in the 1960s separared into the Ancient Church of the East and the Assyrian Church of the East) which embraced Nestorianism in many of its provinces in the Persian Empire for a few centuries, before adopting the Chalcedonian Christological premise under Mar Babai the Great, the Oriental Orthodox, who follow the exact Christology of St. Cyril drafted in response, and the Chalcedonians, who use what I regard to be an adequate but overly complicated formula, which caused the Oriental Orthodox to separate from us over legitimate concerns we had over-reacted to the problem of Monophysitism, which we falslely accused the precursor of the Coptic Orthodox of teaching, when they had anathematized Eutyches and the Monophysites, who then embraced tritheism in the sixth century before becoming extinct.
Now this schism has had a transient property, so there have been periods of restored communion between the three groups, most recently between the Eastern Orthodox and Oriental Orthodox, but under the influence of Old Calendarists, Armenian, Georgian, Russian and Ukrainian nationalists, and misguided Greek, Romanian and Ethiopian monks who have never met a member of the other church, there are many actively seeking to undermine the work of the International Orthodox Theological Association and preserve the EO-OO schism despite the theological dialogue being successfully concluded and despite the success of ecumenical agreements between the Copts and Alexandrian Greek Orthodox and between the Syriac Orthodox and Antiochian Orthodox in preserving the Christian population in Egypt, Syria, Lebanon and Iraq, where the four churches converge.
This shows just how damage continues to be caused by the violent persecution Nestorius initiated against members of the Church of Constantinople who insisted on using the traditional term “Theotokos” taught by St. John Chrysostom vs. his preferred “Christotokos.” Conversely, unlike his opponents, and unlike St. Chrysostom, who was death marched for calling out the consort-Empress of Emperor Theodosius II for wasting money on a solid gold commode, Nestorius lived out his life peacefully in exile and wrote a self-serving biography, the Bazaar of Heraclides, and his supporters in Antioch emigrated to Nisibis where they proceeded to spread his teaching into the church in the Persian Empire.
Thus contrary to what some will tell you, no one has ever been persecuted by the Orthodox for rejecting any Orthodox doctrines concerning the Theotokos. In the case of the Roman Catholic church, the status of Mary was not the main issue with the Protestant reformation; the followers of St. Jan Hus venerated her (which is why he’s venerated as a saint by the Orthodox Church of the Czech Lands and Slovakia) as did the Martin Luther, who actively prayed an Orthodox version of the Hail Mary, as my friend
@MarkRohfrietsch likes to point out, but not the intercessory prayers we use, but not seeking the intercession of the theotokos has never been regarded as a theological error (although I do strongly reccommend it from personal experience), whereas not venerating the Theotokos was classified as such by St. Epiphanios in the late fourth century, and if memory serves the Second Council of Nicaea also directed this, as did equivalent Oriental Orthodox canons and liturgical practices.
Widespread rejection of the veneration of the Theotokos did not become a thing until Calvinism in the 16th century, but even Calvin was not a Nestorian, admitting the Theotokos was a perpetual virgin and the Mother of God.
