-A8
You don't build doctrine on what the text doesn't say. You build it on what it does say. The text SAYS that Joseph didn't know Mary UNTIL she had Jesus. It doesn't stop with Joseph didn't know Mary. It never says that Joseph NEVER knew Mary. But the Catholic (and Orthodox) teaching builds doctrine on what SCRIPTURE doesn't say. They do so based upon tradition, which is fine, but don't say that it is Scriptural. It is not. It says, he didn't know her UNTIL... and that Jesus was her FIRST BORN Son, and that Jesus's Brothers and Sisters were travelling with Mary and calling for Jesus. Jesus was an adult at the time. Why would it take all of the adults in Jesus' family and Mary to go check up on where Jesus was? If the Catholic interpretation is correct and these were Joseph's kids from an earlier marriage, you have to believe that the daughters of Joseph in turn never married (because it would be unlikely that Mary would be gathering them out of their husband's family's house to go get Jesus) and that all of the males in Joseph's family were otherwise doing nothing at the time Jesus was preaching. It makes more sense that these are younger siblings of Jesus, half-brothers and sisters of the Lord and they went with their mother to go check on their brother.
Examples of "until" that do not mean that something happens afterwards...
Regards