This is a Dogmatic belief of all of the Catholic faith, the Orthodox faith, many of the Lutheran and Anglican communities and has roots documented back to at least the second century Anno Domini.
Saint John Chrysostom defended perpetual virginity on a number of grounds, one of which was Jesus’ commands to his mother in Calvary: “Woman, behold your son!” and to his disciple “Behold, thy mother!” in John 19:26-27.
Since the second century these two statements of Jesus from the cross had been the basis of reasonings that Mary had no other children and “from that hour the disciple took her unto his own home” because after the deaths of Joseph and Jesus there was no one else to look after Mary, and she had to be entrusted to the disciple.
Luther, Zwingli and Bullinger all taught this as well as did John Wesley.
As I said above, I know the history of the teaching quite well and have done a lot of reading on it. I want to know why it is important theologically.
So you believe it simply because it is dogma? If so that is fine. That is what I am asking.