Efforts To Tamper With The Text
Marcionites Eliminated Jesus Had a Father/Mother/Brothers
Tertullian in 207 A.D. was defending that Jesus was born a man although simultaneously God was indwelling that man. The heretics were saying Jesus did not have true human flesh because Jesus was God. Or they claimed Jesus had angelic substance. Tertullian points out that to sustain this argument the heretics - -the Marcionites in full context -- altered portions of what was apparently Luke 8:19-21. They erased the fact Jesus had a mother or brothers and sisters:
First of all, nobody would have told Him that His mother and brethren were standing outside, if he were not certain both that He had a mother and brethren, and that they were the very persons whom he was then announcing,—who had either been known to him before, or were then and there discovered by him; although hereticshave removed this passage from the gospel, because those who were admiring His doctrine said that His supposed father, Joseph the carpenter, and His mother Mary, and His brethren, and His sisters, were very well known to them. But [the heretics claim] it was with the view of tempting Him, that they had mentioned to Him a mother and brethren which He did not possess. The Scripture says nothing of this, although it is not in other instances silent when anything was done against Him by way of temptation. (Tertullian, 207 AD On The Flesh of Christ ch. 7.)
Tertullian reasons that Jesus' brothers and apparently Mary did not adhere to Him at the time, and so the Gospels portray a very realistic situation that can happen in any family. It also may explain why Jesus said one must be prepared to be rejected by one's own family. Tertullian explained:
“The Lord’s brethren had not yet believed in Him.” So is it contained in the Gospel which was published before Marcion’s time; whilst there is at the same time a want of evidence of His mother’s adherence to Him, although the Marthas and the other Marys were in constant attendance on Him. In this very passage indeed, their unbelief is evident. Jesus was teaching the way of life, preaching the kingdom of God and actively engaged in healing infirmities of body and soul; but all the while, whilst strangers were intent on Him, His very nearest relatives were absent. (Id.)
Interestingly, this opens up the question whether the Marcionites insisted that the virgin birth took place and that Mary remained a virgin and never had any other children. Apparently not, as the first 2 chapters of Luke are missing in the only gospel the Marcionites used. This raises the question why would the Marcionites be deleting chapters from Luke that include the virgin birth which would lend support to their idea that Jesus was not born human if it was present? This may suggest along with other lines of evidence that the virgin birth account was not originally present in Luke. In any event, despite later Catholic doctrine to the contrary, you can see that Tertullian, a voice of orthodoxy at the time, affirmed the Gospels did say Jesus had brothers.