First, I can understand non-Catholic’s fury and frustration at the prospect of the Catholic Church defining another dogma making Mary co-redemptrix and co-mediator with Christ. Personally, I hope the Church doesn’t define such a dogma because of the obstacle it would create in ecumenical relations. However, I do want to explain what we mean by such terms. We do not mean that Mary is a co-redeemer or co-mediator with Christ in such a way that she is equal to him. ‘There is one mediator between God and man, the man Christ Jesus’ (I Tim. 2:5) Mary is not another mediator. Instead we believe that she works with Christ for the redemption of the world. She mediates with Christ for the salvation of souls. As such she is a model of what we should all be doing. All of us are called to be ‘God’s co-workers’ (I Cor. 3:9) and Saint Paul speaks of the possibility of ‘completing what is lacking in Christ’s afflictions’ through the suffering in our own lives. (Col 1:24) In such a way we believe Mary co-operates with Christ for the salvation of the world. In doing so she shows the whole Church how to share in his saving work.
I can understand your second point too. It looks like the Catholic Church has added lots of beliefs about Mary that are not substantiated by Scripture. I expect you’ll pick up on one or two other items before we’re finished, but let me first say that our Marian beliefs spring from the very earliest traditions of the Church. Justin Martyr and Irenaeus—both writing in the second century—spoke of Mary as the ‘new Eve.’ As such she was considered totally pure.
Finally, you are unhappy with Mary because there was a ‘cult of the girl’ in ancient Rome. Your implication is that Mary is sort of like a good Catholic boy’s pin-up. I’d be careful on this one. When you play the armchair psychiatrist and start finding deep sexual motivations for religious devotion it’s a bit like opening Pandora’s box. Before long you can theorize that homosexuals are attracted to muscular Christianity because they get to love the perfect man, and maybe Protestants (who can’t stand Mary) have a mother-hatred complex.
This kind of speculation is both sordid and specious. Furthermore, your theory doesn’t account for the army of Catholic women who have a deep and abiding devotion to Mary. Anyway, for Catholics Mary has never been seen as the ideal wife or lover. Instead she is the ideal mother. When Jesus looked down from the cross at his beloved disciple and Mary he said, ‘Woman behold your son. Son behold your mother.’ We put ourselves in John’s place and accept that maternal relationship with Mary which Jesus himself gave to his disciples.
I’ve been on the defensive here, and that’s okay. But let me fire one back. In Luke 1.48 Mary says, ‘From now on all generations will call be blessed.’ Why do so many Evangelicals have this big Mary-block? You said we get emotional and our heads turn to putty when Mary comes up. I want to know why Evangelicals’ heads and hearts both turn to stone when Mary comes up. Mary said ‘all generations shall call me blessed.’ Catholics rejoice to call her blessed. It’s something we’re enthusiastic about. So why do Evangelicals go all frosty and seize up?