Mary the Magdalene, The Gospel of Philip, and John 19:25

 Mary the Magdalene was prominent in the Jesus movement because she is mentioned first when she is listed with others (Matt 27:56; 27:61; 28:1; Mark 15:40. 47; 16:1; Luke 8:2; 24:10). Only in John 19:25 is she named after others:

Εἱστήκεισαν δὲ παρὰ τῷ σταυρῷ τοῦ Ἰησοῦ ἡ μήτηρ αὐτοῦ καὶ ἡ ἀδελφὴ τῆς μητρὸς αὐτοῦ, Μαρία ἡ τοῦ Κλωπᾶ καὶ Μαρία ἡ Μαγδαληνή.
Now there stood by the cross of Jesus his mother, and his mother’s sister, Mary of Clopas, and Mary Magdalene.

It is no dishonour for Mary the Magdalene to be named after the mother of Jesus and his aunt, for these were senior relatives of Jesus. Consider how the brother of Jesus is named ahead of even Peter at Gal 2:9. Mary of Clopas is not preceded by καὶ (and), so she may be the aforementioned "his mother's sister". However, the Magdalene's prominence is reduced if Mary of Clopas is seen as a person in her own right. The Magdalene would then be judged to be less important than Mary of Clopas, who is not named anywhere else in the New Testament.

The Gnostic Gospel of Philip (3rd century), like the Gnostic Gospel of Mary chapter 9, promotes the authority of Mary the Magdalene. It does so, for example, by saying that she always walked with Jesus and was called his companion:

There were three who always walked with the Lord: Mary, his mother, and her sister, and Magdalene, the one who was called his companion. For his sister and his mother and his companion were each a Mary.

The first sentence here, like John 19:25, refers to Mary the mother of Jesus, and her sister, and Mary the Magdalene, but it omits Mary of Clopas. This suggests that the author might be equating Mary of Clopas with the aunt of Jesus. The second sentence says that three women were called Mary, but the point is that the sister is called Mary. This is clear from the fact that the sister is mentioned first, ahead even of Jesus's mother, and the fact that the audience already knew that the other two women were called Mary. 

The "his sister" makes little sense, since no sister of Jesus has been in view. As others have suspected, the text, which survives only in a single coptic manuscript, has been corrupted. I believe that the original read as follows:

There were three who always walked with the Lord: Mary, his mother, and her sister, and Magdalene the one who was called his companion. For his mother's sister and his mother and his companion were each a Mary.

The second sentence then works as a clarification of the first, with the same three people mentioned. It claims that Jesus's aunt was called Mary and thus it interprets John 19:25 to mean that Mary of Clopas was Jesus's aunt. It tries to rebut those who would use John 19:25 to argue that the Magdalene was a lesser character. Some found it unlikely that two sisters (the mother of Jesus and her sister) would have the same name, so it is not surprising that someone omitted "mother's". Others came up with different solutions to the problem of two sisters called Mary:

Eusebius (Church History 3.11) states that "Hegesippus records that Clopas was a brother of Joseph." This would make good sense of John 19:25 if "sister" there is interpreted loosely as "sister-in-law".

The Gospel of Pseudo-Matthew (7th to 9th century)

Jesus met them, with Mary His mother, along with her sister Mary of Cleophas, whom the Lord God had given to her father Cleophas and her mother Anna, because they had offered Mary the mother of Jesus to the Lord. And she was called by the same name, Mary, for the consolation of her parents.

In summary, the Gospel of Philip tries to prevent John 19:25 being used to undermine the status of Mary the Magdalene. This seems to have been missed by scholars, probably because they have not been sufficiently attentive to the importance of name order.