As a confessional Lutheran I’m baffled by Baptist/Evangelicalism. This is a hard teaching for most Protestant. They get hung up on “brothers” and calling the Blessed Virgin Saint Mary the Mother of God (not all). Many suffer from “Romeaphobia” for the sake of being anti-Roman Catholic.
On the subject of semper virgo of Mary, exegetically, the perpetual virginity of Mary is 100% plausible. Any honest Theologian cannot dogmatically deny the perpetual virginity of Blessed Virgin St. Mary.
It cannot be proven exegetically from sacred scripture and the church fathers that Mary had children, that so many Protestants enthusiastically insist, then berate those who side with what the historic church has always taught. This ideas that the Blessed Virgin St. Mary (She is the Ark of the living God. The Theotokos) was not a perpetual virgin is novel and runs contrary to the historic church.
Even Calvin, Charles and John Wesley, and even Zwingli of all people (the error of Nestorius was resurrected by Zwingli) etc., adhered to the perpetual virginity of the Blessed Virgin Saint Mary. In most cases it really comes down to having a low view of Christology.
Isa 7:14 Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
Dr. Martin Luther Isaiah 7:14 (LWV16): She shalt conceive. In Hebrew it is “has conceived,” and that is the indication of a miracle; it is as if the prophet were already seeing it. Again, since he says that it is God’s sign, it is necessary that that conception and birth be in a different manner than is commonly and naturally the case, for it would not be a sign if one who today is a virgin would become pregnant after a half year. Therefore she has to be both a virgin and with child. Matthew 1:21 f. clearly explains this.
Immanuel. This describes what kind of person it will be. This is not a proper name. He is indeed the Son of a virgin, and yet He is “God with us,” therefore God and man.
If the Blessed Virgin St. Mary had other children (St. Joseph was dead) then why was she entrusted to Apostle John at his Crucifixion if she had other natural sons to care for her (Jn 19:26–27)?
Mark 6:3 brother … his sisters: Jesus’ cousins or more distant relatives. They are not siblings from the same Virgin Mother.
1. These brethren are never called the children of Mary, although Jesus himself is (Jn 2:1; 19:25; Acts 1:14).
2. Two names mentioned, James and Joseph, are sons of a different “Mary” in Mt 27:56 (Mk 15:40).
3. It is unlikely that Jesus would entrust his Mother to the Apostle John at his Crucifixion if she had other natural sons to care for her (Jn 19:26–27).
4. The word “brethren” (Gk. adelphoi) has a broader meaning than blood brothers. Since ancient Hebrew had no word for “cousin”, it was customary to use “brethren” in the Bible for relationships other than blood brothers. In the Greek OT, a “brother” can be a nearly related cousin (1 Chron 23:21–22), a more remote kinsman (Deut 23:7; 2 Kings 10:13–14), an uncle or a nephew (Gen 13:8), or the relation between men bound by covenant (2 Sam 1:26; cf. 1 Sam 18:3). Continuing this OT tradition, the NT often uses “brother” or “brethren” in this wider sense. Paul uses it as a synonym for his Israelite kinsmen in Rom 9:3. It also denotes biologically unrelated Christians in the New Covenant family of God (Rom 8:29; 12:1; Col 1:2; Heb 2:11; Jas 1:2).
I’m 100% certain the Blessed Virgin Saint Mary, the Ark of the living God, the mother of God, birthed no other children and remained a Virgin; before, burning and after His birth. The perpetual virginity of the Blessed Virgin Saint Mary cannot exegetically be disproved.
https://ref.ly/o/lw16/224163?length=410 via @Logos
Hope that helps. May God’s grace and peace be with you.