Ok, where to begin, where to begin...
My favorite explanation on the perpetual viginity is Luke 1:31,34 -
"the angel tells Mary that you "will" conceive (using the future tense). Mary responds by saying, "How shall this be?" Mary's response demonstrates that she had taken a vow of lifelong virginity by having no intention to have relations with a man. If Mary did not take such a vow of lifelong virginity, her question would make no sense at all (for we can assume she knew how a child is conceived)"
Sheer eisegesis. Iirc, the direct translation is actually better stated "I am not knowing a man" as in she wasn't currently having sexual relations, because she wasn't married yet. Also, did the angel put a time frame on the conception? You have to read into it, that she took a vow of virginity. I would think such a vow, of a supposedly sinless woman, would be rather important, and be more explicit than the possible tense of a single word.
My favorite on the assumption is Rev. 12:1 -
"we see Mary, the "woman," clothed with the sun. While in Rev. 6:9 we only see the souls of the martyrs in heaven, in Rev. 12:1 we see Mary, both body and soul." The woman can also be interpreted as the Church.
The RCC disagrees with you:
* [12:1] The woman adorned with the sun, the moon, and the stars (images taken from[bless and do not curse]Gn 37:9–10) symbolizes God’s people in the Old and the New Testament. The Israel of old gave birth to the Messiah (Rev 12:5) and then became the new Israel, the church, which suffers persecution by the dragon (Rev 12:6,[bless and do not curse]13–17); cf.[bless and do not curse]Is 50:1;[bless and do not curse]66:7;[bless and do not curse]Jer 50:12. This corresponds to a widespread myth throughout the ancient world that a goddess pregnant with a savior was pursued by a horrible monster; by miraculous intervention, she bore a son who then killed the monster.
http://www.usccb.org/bible/revelation/12. The above is the only explanation given of Revelation 12:1, and also note they mention she gives birth in pain. For that to be true would indicate a natural birth, thus negating the ever virginity.
Similar are the doctrines of the Triune God and the Hypostatic Union. Both CANNOT be absolutely proved using scripture alone. Scripture only points to the ideas. Why do you accept the dogmas of the Trinity and the 2 nature's of Christ as taught by the RCC without absolute scriptural evidence?
This is utter hogwash. The doctrine of the Trinity is shown throughout scripture, sometimes implicitly, sometimes explicitly, but easily found.
I'll ask you the same question....show me in scripture the doctrine of the Trinity and the doctrine of the 2 nature's of Christ.
Start with the 2 natures:
John 1:1,14
Col. 2:9
Hebrews 1:3
There are many more especially when you start putting together the verses where one says He is man, while another in another book says He is God, but don't expressly say them together.
Trinity:
Matt 28:19
1 Cor. 12:4-6
2 Cor. 13:14
Again there are others, but you get the drift. So again, outside of eisegesis, there is zero evidence of those Marian dogmas. I appreciate the attempt though. It was more than your fellow Catholics were willing to do.