The analogy of Mary and Michal is really a false one. I was just trying to show the context of the word "until". I agree that the verse in Matthew cannot be used to prove Mary's virginity, but niether can it be used to say that Mary and Joseph engated in the marital embrace after.
We should remember that none of us use the true Bible, since it was written in Greek and Hebrew. We all use interpetations of the Bible, since we read it in English. Frequently the full meaning can be lost or twisted (as we know by those condemning all nudity). Another point of trivia is that the Table of Contents, the Chapter designations and the Verse designations are not really part of the Bible. The ToC was established in the 4th century, the chapters and verses in the 10th or 13the centuries. Of course the ToC became an issue between the Catholics and the Protestants again in the 16th century.
Another thing to ponder comparing Mary to the Ark is that in the OT, the man who touched the Ark (to prevent it from falling off the ox cart) was struck dead. That is when King David sent the Ark to the House of Obededum for 3 months prior to bringing it to Jerusalem. Similarily, Mary visited Elizabeth for 3 months. Would Joseph likewise have been struck dead if he had marital relations with Mary. Catholics also believe that Mary was the spouse of the Holy Spirit, That is how she concieved and God always follows the law. Marriage first, Children second. In this analogy Joseph would have been commiting adultury if he had maritial relations with her.
Tim Staples, a Catholic convert from Assemblies of God, has a tape series where he talks for 10 or 12 hours about this kind of stuff. He brings out nothing new that has not been consistant with the Catholic Church teaching throughout the ages.
Remember, I am not trying to convice you but rather point out some things that the Catholic Church teaches.
Thanks for the opportunity to explain a bit about what Catholic believe.