This is the beginning of an answer to Kurt’s question about Mary. And, as is the case with many doctrinal issues, the real issue is found at the level of the presuppositions.
The question really is not whether the Roman church has a nuanced position on Mary that acknowledges that Christ is a “unique” mediator. I have no doubt that in the schematic catechism it would all be worked out carefully. They have done the same thing with the word worship — latria, hyperdulia, and dulia. This goes here, and cannot go there, and so forth. The whole thing is covered on paper. My problem is that when we bring it down from the realm of abstractions, what actually happens in the world where regular people pray? What actually happens is that people render “worship” to creatures that is on a practical level indistinguishable from the worship they render to God, and this is the definition of idolatry.
Which brings us to the question of the communion of the saints, and of Mary’s mediatorial role. A standard question that is asked of Protestants is, “don’t you all pray for each other?” What is the difference between saint A praying for you and saint B? Why do we privilege saint A in this matter just because he is alive and made it to your Wednesday night prayer meeting? Why cannot deceased saints join in with the prayers?
The answer has to do with the assumption that is being made when a prayer request is offered to a deceased saint, or to Mary (also a deceased saint). When I ask my friend Bob to pray for me because I have an appointment with the surgeon tomorrow, I do not have to assume any superhuman powers on the part of Bob in order to make the request of him. I know he heard me, because he was right there, and he heard the prayer request on exactly the same principles in play when he heard me ask him to pass the mashed potatoes. But when one person is caught in a storm at sea and cries out to Mary, and another at the same moment is struggling with his personal finances in Australia, and asks Mary to pray for him, this cannot be done without assuming that Mary has all the functional attributes of Deity.
Now it would not rock my Protestant world at all if I died and went to heaven, only to discover that at some point in my worldly sojourn, Mary had stumbled across some aspect of my story and prayed for me. “Oh my. Look at that poor sap there.” But for me to ask her to do this assumes that she has a relationship to the world, and to everyone in it, including me, that Scripture does not give me any basis for believing. Of course I do not believe that departed saints cease to love their friends and brothers back here on earth. So the issue is not whether the saints in heaven can pray for Christians on earth. Why would they not be able to? This is part of the communion of saints.
The issue is what we have to assume about them in order to ask them to do so. And what we have to assume is that they can hear us. We do not have any encouragement from the Bible for believing this, and if we just go ahead and do it anyway, we are failing to make an important practical distinction between God who hears my every thought, and my Uncle Leonard, now with God, who does not.
The communion of saints means that the body of Christ is a glorious and unified mystery. It means I am one with all the saints in heaven, just as I am one with all the saints alive today in China. But if I were crossing a street, saw a truck with no brakes hurtling toward me, and cried out, “Wang Tu, pray for me!” my problem is simple to identify. I am assuming that the doctrine of the communion of saints gives Wang Tu greater hearing abilities than in fact he actually has. So the problem is not heavenly saints praying. The problem lies, not in the praying there, but in the prayer requests here.
If I assume that the saints in heaven can hear my thoughts, my murmured prayers, my unspoken requests, and what I write down, then I am necessarily assuming that from my perspective, I cannot distinguish their abilities from God’s, at least as far as those abilities touch me. Since I have no encouragement from the Bible to make such assumptions, and since such assumptions have done much superstitious damage in the church, it is my view that it is the responsibility of faithful Christians to stay far away from them.