According to my reading of history, the medieval Catholic Church was afraid of the secrets that groups like the Knights Templar and the Cathars possessed, and in turn this caused a flurry of hate, wars and rebellion.
Why did this occur? We have to consider how powerful the Catholic Church was in terms of influence and wealth. The church eventually righted itself in the wake of the reformation led by Martin Luther. and the Anglican Church in England. However, as Catholics and Protestants fought over who would rule the Western world’s Christians, both factions put Jesus on the back burner. Both took on Paul’s interpretation of Christ’s life and teachings, turning him into the son of God who was crucified and resurrected. In no way could they accept that Jesus was married or had children, for that would keep him from being divine. Without the death on the cross, there’s no way to afford guilt to all of those who were told that “he died for our sins,” and there would be no premise of the resurrection. So this led to a severe editing of the Bible