The problem here is that the whole riff on "deaconesses", Mary Magdalen, and the Gnostics was created specifically to attack the Catholic Church. It has no basis in historical fact.
A bunch of people believe it solely because they were deluded by Dan Brown and his ilk in the popular press. If scores of people run around in a panic because they believe that Martians are landing in Grover's Mill, that doesn't make it true just because a lot of people believe it. It just makes them victims of a hoax.
Moreover, Brown may well just be in it to make money, but plenty of liberals within the Church push that garbage because they want to recreate the Church in their New Age image.
If you don't like the word 'garbage', we can say, 'deliberately manufactured falsehood to discredit Catholic beliefs'.
They're coming for all Christians next, you know.
We know. Speaking as a Protestant I consider Roman Catholics as my brothers and sisters. I do not agree with all the doctrines of your church, and hence am not a member, but the days when we could afford to give in to division and hatred because of arguments among theologians and seminarians are long past. I feel much the same way about Jews.