
Now, I know that we Catholics don't actually believe that Mary "ascended," so I passed on my Wii remote, and tried to work my way over to the conversation. But by the time I made it over there they were talking about a sick family member. Not something I wanted to interrupt for a possible argument. So, I haven't yet been able to correct the misunderstandings (though I plan to find a way).
The thing that really got me, though, was the, "They actually believe that." I do understand this unhealthy attitude of superiority. I've made the same mistake myself, to a small extent with Protestants, and to a more major extent with Mormons.
But, as far as the Assumption, the Immaculate Conception, and a few other Marian doctrines are concerned, I'm not quite sure why they are so incredulous that we might believe such things. They are not without precedence: Elijah being assumed, Adam and Eve not having original sin, etc. The Bible never says, "Mary sinned," or, "Mary died, was buried, and rotted in the ground." And early Church history doesn't show evidence that these things weren't true. Even Luther, Calvin, and (sometimes) Zwingli believed most of the Marian doctrines. Apparently the Bible doesn't clearly deny them.
Because these Protestants believe the Bible is the only real source for history of the early Church, I can see how these beliefs might appear to be manmade, since they are certainly not explicit in the scriptures. But there is nothing so strange or unbiblical about any of them (properly understood) that warrants a, "They actually believe that."
But then, thinking that Mary ascended under her own power (as Christ did), rather than being assumed by God (as Elijah was assumed in 2 Kings 2:11), would make it fairly absurd. This would go along with the belief some Protestants have, that Catholics worship Mary as a Goddess. Considering this horrible misunderstanding, I suppose I'd have to have the same reaction.
"Do they actually believe that?!?"
Thankfully, the answer is, "No, we don't."
I'll probably give a quick defense of the Catholic Marian doctrines at some point in the future, but for now, here's some good links on the subject:
Mother of God