You have a source to read that up? At least in 452, they (some) were already pretty sure about her being virgin.
Dioscorus then moved to depose Flavian of Constantinople and Eusebius of Dorylaeum on the grounds that they taught the Word had been made flesh and not just assumed flesh from the Virgin and that Christ had two natures.
OP might be confusing the adipartheos of Mary - the belief that she was a virgin before, during and after the birth of Christ. Some even go as so far as to imply Jesus wasn’t born like a human and emerged in some other way, which I’ll leave to the readers imagination.
You have a source to read that up? At least in 452, they (some) were already pretty sure about her being virgin.
https://en.m.wikipedia.org/wiki/Council_of_Chalcedon
452 is after 300 so that would be consistent with OP, however, here’s a “source” such as it is claiming her virginity in 150 AD https://en.m.wikipedia.org/wiki/Gospel_of_James
OP might be confusing the adipartheos of Mary - the belief that she was a virgin before, during and after the birth of Christ. Some even go as so far as to imply Jesus wasn’t born like a human and emerged in some other way, which I’ll leave to the readers imagination.