How about these??? Matt. 1:18 This is how the birth of Jesus came about. His mother Mary was pledged to be married to Joseph, but "before they came together", she was found to be with child through the Holy Spririt.
Matt. 1:25 But he had no "union" with her until she gave birth to a son. And he gave him the name Jesus.
John 2:12 After this he went down to Capernaum with his mother and brothers and his disciples. (Why mention both brothers and disciples if they were one and the same?)
Acts 1:14 They all joined together constantly in prayer; along with the women and Mary the mother of Jesus, and his brothers. (The previous verse mentions all the disciples..so again, why the specific distinction?)
Matt. 12:46 While Jesus was still talking to the crowd, his mother and brothers stood outside, waiting to speak with him.(His answer indicated that all his disciples were inside with him...verse 49.)
Luke 2:7 And she gave birth to her "firstborn", a son. She wrapped him in strips of cloth and placed him in a manger, because there was no room for them in the inn.
These passages from Holy Scipture are very plain...and this is the reason Mary did not have perpetual virginity. There is much written to indicate she had a very large family. There is nothing written to indicate she was forever a virgin. The only proof from your quarter is your tradition. Your tradition is lacking.
I am not a protestant! Never been one. Don't buy most of what they say either.
Actually, because of your misunderstanding, these passages are not as plain as you think. Matt 1:18 and 1:25 are only referring to Mary's virginity prior to the moments mentioned. The usage however does not imply that her virginity did not continue afterward.
In the various references to "brothers" read "male relatives", which is what would have been understood in Aramaic.
"First born" in Luke 2:7 is a technical term and refers to the requirement that the first born male child must be redeemed from God under the Mosaic Law. It does not indicate that there must be a second born, etc. A male only child is still a "first born".
Another consideration regarding Christ's possible brothers would be that Christ would not declared her a mother of his disciple at the Cross if there had been another son of hers to take care of her after Christ's death.
There is much written to indicate [Mary] had a very large family. There is nothing written to indicate she was forever a virgin.
Muich written? When? By Whom? The belief of Mary's perpetual virginity is at least as old as Protoevangelium of James, early 2 century. This specifically mentions that Mary had been consecrated to the Lord and had a vow of virginity since childhood. Joseph was chosen to be her nominal husband. He was an old man and had children from previous marriage. Those were Christ's brothers in the loose sense of the world.
Patristic references to Mary's perpetual virginity are quite numerous.