Answer
Similar to the Gospel of Thomas, the Gospel of Philip is a collection of sayings, supposedly of Jesus. The Gospel of Philip focuses a great deal on the “sacrament of marriage” as a “sacred mystery.” The Gospel of Philip does not claim to have been written by Jesus’ disciple Philip. It is titled “the gospel according to Philip” due to Philip being the only disciple of Jesus who is named in it (73:8).
The most complete manuscript of the Gospel of Philip was discovered in the Nag Hammadi library in Egypt in 1945. It is written in the Coptic language and is dated to approximately the 4th century AD The Gospel of Philip is a Gnostic gospel, presenting a Gnostic viewpoint of Jesus and His teachings. While there are a few verses in the Gospel of Philip that resemble the four biblical Gospels, a reading of the Gospel of Philip will reveal many irreconcilable differences and a completely different message regarding who Jesus was and what He came to do.
Of most interest in the Gospel of Philip is what it has to say about Jesus’ relationship with Mary Magdalene. In his popular book The Da Vinci Code, author Dan Brown points to the Gospel of Philip as evidence of Jesus’ marriage / relationship with Mary Magdalene. However, the Gospel of Philip nowhere states that Jesus was married to Mary Magdalene. It does not even state that Jesus was romantically involved with Mary. The one section that deals with this issue is heavily damaged, with several portions unreadable. Here is what the Gospel of Philip states, with “…” representing missing portions: “and the companion of the … Mary Magdalene … more than … the disciples … kiss her … on her … the rest of the disciples … they said to him … why do you love her more than all of us?” Even if we assume that Jesus was kissing Mary Magdalene, the text does not imply anything other than a friendly relationship. A single man kissing a single woman on the cheek, while rare in that culture, is by no means indicative of a romantic relationship.
Whatever the case, even if the Gospel of Philip explicitly stated that Jesus was married to Mary Magdalene, that would not make the idea true. The Gospel of Philip was not written by the Apostle Philip or anyone who had ever met Jesus. The original writing of the Gospel of Philip is dated to the 3rd century AD at the earliest, at least 200 years after Jesus’ death. The only value in studying the Gospel of Philip is in learning what heresies existed in the early centuries of the Christian church.