The other common modern scriptural objection to the doctrine of the perpetual virginity of Mary is found in Matthew 1:24-25.
Then Joseph, being aroused from sleep, did as the angel of the Lord commanded him and took to him his wife, and did not know her till she had brought forth her firstborn Son. And he called His name JESUS.
This is actually a pretty weak objection. With ’till’ or ‘until’, sometimes the condition leading up to the event changes after the event and sometimes it doesn’t. That’s easy to illustrate with just a couple of examples, but there many examples of both usages in the New Testament.
And when it was day, some of the Jews banded together and bound themselves under an oath, saying that they would neither eat nor drink till they had killed Paul. (Acts 23:12)
The above is an illustration of a usage where the condition (not eating or drinking) is expected to change after the event (killing Paul). That’s pretty obvious from the context.
For He must reign till He has put all enemies under His feet. (1 Cor. 15:25)
I think most Christians would agree that Christ will continue to reign after all enemies are under his feet, but that’s incidental to the point being made. In this case the condition (Christ reigning) continues after the event (putting all enemies under his feet).
The whole point being made in Matthew is that Mary conceived as a virgin and gave birth to a son who was conceived by the Spirit and then immediately moves to his name, which is an important one, Jesus. Matthew is saying nothing about what happened between Mary and Joseph after the birth of Christ. All that can really be said from the context is that there is not information to conclude whether or not the condition (Joseph not knowing Mary) changed after the event (the birth of Jesus). There’s certainly nothing in the text that refutes the long-standing and ancient tradition of the Church.
And once again, it’s not as though some modern Protestants suddenly discovered a new text in Scripture that the ancient Church knew nothing about. They were certainly familiar with Matthew and were more closely connected than us to the language, culture, and customs that formed the context for the text. Why would we assume we understand the text better than they did? That attitude puzzles me.