And Mary said, “Behold, I am the servant of the Lord; let it be to me according to your word.” And the angel departed from her.
That's the closest I can find concerning vow, and it's not what you say... Where are you guys getting that she made a vow of perpetual virginity?
The vow itself is not written in scripture, but the only way the interaction between Mary and the Angel would have happened is if Mary didn't intend to ever have relations with Joseph.
Then said Mary unto the angel, "How shall this be, seeing I know not a man?" ~ Luke 1:34
Catholica, don't tell me that is the source of the Roman Church making Mary into a perpetual virgin... Gabriel told Mary she would have a kid, and she was confused because she never laid with a man before. It was simply a bewilderment, like winning the lottery even though you never played it. Gabriel then answered it would be by the Power of God and the Holy Spirit upon her, and she accepted it. That's not a vow...
1. This verse isn't the source of the Catholic Church's teaching about Mary's perpetual virginity. In all likelihood, the fact that the Catholic Church took care of Mary throughout her public life, and knew her personally... that likely is the source. However the verse I noted is support for that fact.
2. The angel didn't say that she was already pregnant. The angel told her that she "Will" conceive. That means, future. In normal human understanding, that would indicate to someone that the conception would take place in the normal way, and in the future. Mary's response indicates that she didn't intend to ever take part in the "normal way" of conceiving. And that is the support here for her perpetual virginity.
3. I didn't claim that this scripture is the vow, and I even wrote that it is not the evidence for her vow. It is just evidence that she didn't intend to "know" Joseph. The "vow" is simply the explanation of why that was the case.
If you just read the scripture for the words it says and try to remove those preconceived notions of what was happening, I hope that this exposition will become clear.
When Joseph woke from sleep, he did as the angel of the Lord commanded him: he took his wife, but knew her not until she had given birth to a son. And he called his name Jesus.
The angel of the Lord didn't command Joseph not to have relations with Mary until she gave birth. And I believe that this is even MORE evidence that the couple had entered into an abstinent caretaker-type marriage. Because that period between conception and birth is one where the husband and wife often have relations.
Furthermore, the use of the word "until" doesn't assure that a future action actually took place. There are many cases in scripture where it does not. Including sayings like "until the day of his death" and "until his enemies are placed beneath his feet". The word is oft use to show a continuous state that exists during a certain period of time. And so scripture's use of the word "until" here doesn't disprove that Mary remained a virgin. Rather, the purpose of this scripture is to show that the prophecy of Isaiah 7:14 is fulfilled perfectly, that a virgin will conceive AND bear a son.
Would Mary have been in sin for laying with her husband after the birth of the Lord? Surely not.
Not in a normal marriage. But if she violated a vow that she made to the Lord, or Joseph demanded that she violate a vow, then yes there would have been sin involved in that act.