What Protestant arguments exist for the perpetual virginity of Mary? It's common knowledge that Roman Catholics and Eastern Orthodoxy have the doctrine of the perpetual virginity of Mary. Protestants generally don't have that belief.

Less known is that Zwingli and Luther believed in perpetual virginity, too. What are the arguments for the doctrine, not assuming papal authority?
There is no clear biblical evidence for the non-Virginity of Mary.


The Bible never says he had full blooded brothers and sisters.  I don't want to delve into translations which I don't understand (Aramaic words for niece, cousin, nephew, etc...), but it is clear that Jesus does however call many people his brothers, and exhorts us all to call others our brothers and sisters, who are clearly not siblings. 
The Bible says Jesus was Mary's 'firstborn' son, but firstborn could be a title given to son's offered to the temple.  Then there's the use of the word 'until', in reference to Mary and Joseph's relations.  But, if I claim to lover and serve the Lord until my dying day, I certainly hope to do so after my dying day!


But there is an inkling of evidence for her not having any other children - although if you accept the brothers in (1.) as being other living sons of Joseph, it confuses the argument.


When Jesus is dying on the Cross (in John's gospel), He instructs His beloved disciple and he takes to take Mary into his house.  If she truly had other sons, that would be moot point for the other sons would have been there to take care of her.


Note, this is not an argument in relation to the doctrine that Mary was still materially a virgin after birth.  That requires adherence to the Dogma.

Virginity itself is not altogether uncommon in human history (Vestal Virgins, Jewish Virgins). Having a Child while remaining a virgin, is a singular event worthy of our Creator and Redeemer.