In 591, Pope Gregory (The Great), preached a sermon in which he conflated three NT women into one. He identified Mary of Bethany with Mary Magdalene with the immoral woman of Luke 7, forever casting the image of Mary Magdalene as the immoral woman. To add weight to his argument, the Pope stated that the "seven demons that were driven out of Mary Magdalene" were obviously the seven deadly sins — which only demonstrates that the homiletical practice of "making broad and unsubstantiated assumptions" is nothing new!
His incorrect identification of Mary Magdalene as the sinful woman persisted throughout the Western Church, and western art and literature, right up to the popular "Jesus Christ Superstar," by Andrew Lloyd Weber, and Mel Gibson's "The Passion of Christ," where Mary Magdalene is again, the "loose" woman-turned-convert. Such misinformation makes good copy and good theater, but it's just false! Fortunately, the Eastern Church never made this mistake, always honoring Mary Magdalene as the faithful follower of Jesus that she was. It was only in 1969 that the Roman Catholic Church corrected their view and established July 22 as the Feast Day of St. Mary Magdalene.
Mary Magdalene, from the Sea of Galilee town of Magdala, which is not far from Jesus's primary center of activity, Capernaum, is named twelve times in the NT, far more times than any of the twelve disciples except for Peter, James, and John. She is the first in the list of women who supported Jesus out of their own means. She is there at the crucifixion, when most of the twelve men had fled. She is there when Jesus is laid in the tomb. And she is there on that first Easter morning, the first to see the risen Christ and the first to go and tell the others. This led St. Augustine to call her the "Apostle to the Apostles." Think of how much better and stronger the church would be if it had elevated equally Mary and Peter as its co-leaders!
All this to say that careful work on the text is of utmost importance. What seminaries teach, what pastors learn and proclaim is vitally critical, and can have long lasting implications. We might not have the influence of a Pope Gregory, but we can perpetuate a misconception very easily. Let us be careful in our work; sometimes it can take centuries to undo the damage that has been done.