The oldest Christian traditions, which the Romanists ignore, maintain that this James (pastor of the Jerusalem) was from Mary's womb--and hence, a blood brother of Jesus Christ.
See http://www.FreeRepublic.com/forum/a394d3ff9758a.htm
(Actually, Protestants don't base their position concerning Mary's NON-perpetual virginity on these ancient traditions. We are merely UNsurprised by these traditions. And we dare to cite these traditions as a way of pointing out that RCs seem to be suspiciously selective in their appeals to tradition.
Protestants ultimately base their position on a straightforward reading of Mark 6:3 and Matthew 13:55--coupled with the undeniable fact that cohabitation as husband and wife without any sexual intercourse whatsoever is ungodly and ultimately forbidden in Scripture.)
1. Many Protestants assume that whenever they read of Jesus' "brothers," this is referring to His siblings, other sons and daughters of Mary. But it is not that simple. "Adelphos," the Gk. word for "brother" in the NT, has multiple meanings (like the English word), and they all appear frequently in Scripture. In addition to sibling, it can also denote (1) those of the same nationality (Acts 3:17; Rom 9:3); (2) any man, or neighbor (Mt 5:22; Lk 10:29); (3) persons with like interests (Mt 5:47); (4) distant descendants of the same parents (Acts 7:23,26; Heb 7:5); (5) persons united by a common calling (Rev 22:9); (6) mankind (Mt 25:40; Heb 2:17); (7) the disciples (Mt 28:10; Jn 20:17); (8) all believers (Mt 23:8; Acts 1:15; Rom 1:13; 1 Thess 1:4; Rev 19:10). Clearly, then, this issue is not at all settled by the mere word "brother"/"adelphos" in the Bible, and a more in-depth examination of the biblical data will be necessary.
2. "Brethren" - Biblical Exegesis
A. By comparing Gen 14:14 with 11:26-7, we find that Lot, called Abraham's "brother", is actually his nephew.
B. Jacob is called the "brother" of his Uncle Laban (Gen 29:10,15).
C. Cis and Eleazar are described as "brethren", whereas they are literally cousins (1 Chron 23:21-2).
D. "Brethren" as mere kinsmen: Deut 23:7; 2 Sam 1:26; 1 Ki 9:13; 2:32; 2 Ki 10:13-14; Jer 34:9; Amos 1:9.
E. Neither Hebrew or Aramaic has a word for "cousin." The NT retains this Hebrew usage by using "adelphos," even when non-siblings are being referred to.
F. In Lk 2:41-51, Joseph and Mary take Jesus to the Temple at the age of twelve, with no sign of any other siblings.
G. Jesus Himself uses "brethren" in the larger sense (Mt 23:1,8; 12:49).
H. By comparing Mt 27:56; Mk 15:40; and Jn 19:25, we find that James and Joseph - mentioned in Mt 13:55 with Simon and Jude as Jesus' "brethren" - are also called sons of Mary, wife of Clopas. This other Mary (Mt 27:61; 28:1) is called Mary's "adelphe" in Jn 19:25 (two Marys in one family?! - thus even this usage apparently means "cousins" or more distant relative). Mt 13:55 and Mk 6:3 mention Simon, Jude and "sisters" along with James and Joseph, calling all "adelphoi". Since we know that James and Joseph are not Jesus' blood brothers, it is likely that all these other "brethren" are cousins, according to the linguistic conventions discussed above.
I. Even standard evangelical Protestant commentaries such as Jamieson, Fausset & Brown admit that the question is not a simple one: "an exceedingly difficult question . . . nor are opinions yet by any means agreed . . . vexed question, encompassed with difficulties." {commentary for Mt 13:55}
J. Some Protestant commentators maintain that Mt 1:24-5 ("Joseph knew her not till . . .") implies that Mary had marital relations after the birth of Jesus. This does not follow, since "till" does not necessarily imply a change of behavior after the time to which it refers (cf. similar instances in 1 Sam 15:35; 2 Sam 6:23; Mt 12:20; Rom 8:22; 1 Tim 4:13; 6:14; Rev 2:25).
K. Likewise, "firstborn" (Mt 1:25) need not imply later children. A mother's first child is her "firstborn" regardless if any follow or not (Ex 13:2). Also, in the Bible, "firstborn" often means "preeminent," and even applies to those who are not literally the first child (Jer 31:9), or, metaphorically, to groups (Ex 4:22; Heb 12:23). Thus, "firstborn" in Mt 1:25 actually is more of an indication that Jesus is Mary's only child, than that there were others. This position is held by many evangelical Protestant scholars on these criteria, rather than Catholic dogmatic grounds.
L. Jesus committed his Mother to the care of John from the Cross (Jn 19:26-7). This is improbable if He had full brothers of His own then alive. Again, many Protestant interpreters agree.
M. Who would want to have God for a brother anyway?! Talk about sibling rivalry and an inferiority complex! The whole notion, if pondered, seems more and more improper and unbecoming - out and out implausible, even apart from the biblical data.
3. Early Christian Tradition was unanimous in holding to Mary's Perpetual Virginity. It was first doubted, as far as we know, by one Helvidius, who tangled with St. Jerome in 380, but by few others until recent times. All the Protestant Founders firmly held the belief, as did later notable Protestants such as John Wesley, and many more to this day, on biblical grounds alone.
Item V. from Dave Armstrong's site.
Mary obviously had other children years after Jesus was born - conceived in the normal biological manner, with her husband Joseph. The fact that Jesus was born supernaturally, conceived by the power of the Holy Spirit, does not mean that Mary remained a virgin the rest of her life after Jesus was born. And of course, as you mentioned, procreation in the sanctimony of marriage is a good thing, blessed by God.
I see no troubling aspects to this at all.
Wouldn't the Mary being pregnant by someone else besides her husband be even more ``unGodly and ultimately forbidden?'' By your standard Joseph never should have married her!