So I thought I would relate what I remember of a conversation I had with my sort of Catholic ex-boyfriend during Lent. In elementary school I went to catechism once with a friend and I remember feeling embarrassed when the teacher asked me a question about Jesus and I didn't know the answer. But I also remember that those kids were learning from textbooks! so I figured this guy must have an answer for pretty much anything I could throw at him. I expected him to be able to adequately explain everything he believed at a moment's notice and have it now make sense to me (even though it inherently didn't make sense to me). This resulted in a fight.
Me: So... Catholics believe in transubstantiation which means that the bread and wine at Communion turns into the literal, physical body and blood of Jesus. So Catholics say the communion is not just symbolic and that they are not just spiritually communing, but are physically communing with Christ on a molecular level by both accepting his spirit and divinity AND by eating his body and blood. Isn't the transformation of the bread and wine into physical flesh part just a little detail? Who cares if there is a physical part to the communion? Wouldn't it be better to leave out that little detail and allow Catholics to believe in an actual (i.e. not symbolic) spiritual communion without introducing doubt by insisting that they believe in this weird, magical-seeming process of turning normal food into human flesh? And how does this make sense anyway? Christ doesn't have a physical body anymore because he died a long time ago and it would have rotted away by now.
[Notes: Not believing in transubstantiation makes a Catholic person anathema, i.e. cursed, so it's one of those serious things that could supposedly get someone excommunicated (although that seems like more of an idle threat nowadays, at least in America). Also, I was obviously still pretty clueless about Christianity at this point, forgetting that the resurrected Jesus literally IS zombie-Jesus. Although, in fairness, the resurrected Jesus went to great lengths to convince the disciples that he is not a ghost and, presumably, not a zombie. Anyway, I completely forgot that, according to the New Testament, Christians get their physical bodies back at some point and that Jesus was resurrected with an intact spiritual-yet-physical body--no wonder such a big deal was made about there being no body in that cave, because it got up and wandered off somewhere. Der... but apparently that's a big stumbling block for lots of people. Believing that a soul could exist eternally is no biggie but once a physical body is involved that's going too far.]
Him: Well with God anything is possible, the body and blood of Christ come into being during Communion. So yes, it makes sense and I've never had a problem believing it. And believing that the bread and wine transform into the body and blood is fundamental to being Catholic and the most important difference between Catholicism and other Christian denominations.
["GAH!!!" I thought. "Least helpful answer ever!!!"]
Me (frustrated): But.... isn't it most important to believe that you are having an actual communion with God rather than symbolic? Can't you believe that all of that actual communion is happening on a spiritual level without believing that there has to be some hunk of dead flesh and a puddle of blood in your stomach?
Him: No, the reality of the body and blood is the most important part. Without that how are you having an actual communion?
Me (confused): But.... Jesus taught not to overly value the physical life and our physical bodies so why would he then commune with people through 'pieces' of a physical body? And are you saying that God can't commune with people without having some sort of vessel? which is the body and blood? In which case, why couldn't the bread and wine act as that vessel without magically transforming into flesh? You just said that with God anything is possible. I just don't understand why you have to believe in that detail and why it's important.
[As I would soon realize, the body and blood are not earthly hunks of flesh but more like the physical component of the essence of God and what makes Jesus human rather than some magical energy source. And since God is infinite and can't be broken into pieces the WHOLE body and blood of Christ is supposedly in both the bread and the wine, which is why at the mass most Catholics just take the wafer. And here I thought you needed both body and blood to have a complete set of Jesus ingredients!!]
Him: Well I've never had a problem believing it. I don't know how to explain exactly why. It's a defining belief of Catholicism, you don't have to believe it but if you don't then you shouldn't be Catholic.
[Okay, so this guy's answer was that he believed in transubstantiation because believing in transubstantiation is a defining characteristic of a Catholic, and by whatever twist of fate he is a Catholic.]
Me (super frustrated and getting rude): But how can you believe something without even knowing why? You're Catholic and therefore you believe whatever the religion entails without caring why? That's not a reason, "I believe because I'm Catholic and this is one of the things that Catholics believe." How do you know the Pope doesn't just make this stuff up? I mean, I know he doesn't, but he has to have reasons that make sense. is Catholicism really such a self-righteous club that you have to believe absolutely everything taught or you shouldn't even bother?
[Pointless, heated arguing followed by silence. By the way, at that point I was not at all sure that the Pope doesn't just make this stuff up but thought I was being gracious by giving him the benefit of doubt. You know, he could just be crazy or misguided.]
When we both finally pulled ourselves together and began to talk civilly we ultimately found out that I was missing a huge part of the point of Communion, which I had read about in the gospels but hadn't really understood. Spiritual communion was only part of it, there was also a communion on the human level, something like God coming down to the human level in order to raise us to his spiritual level, reaching down his hand and meeting us partway. So to Catholics, this offering of the body and blood of Christ is a renewal of the sacrifice made by Jesus via the crucifixion. And God renews this experience of the human world by physically communing with it, by allowing people to eat Him. [I guess...]
Me (relieved): Oh!! So it is important then. But how does this hunk of dead, disembodied flesh allow God to experience human suffering? Is this flesh able to feel?
Him: Well I never thought of it as dead, it's living flesh. I don't know if it can feel, I guess I never thought about that.
Me: But can't God just possess us like the demons do and to suffer with us that way?
[Hahaha, I know! Things were getting kinda weird.]
Him: Well we can be possessed but I don't think God would feel our pain just like the demons don't feel the pain of the humans they possess.
Me: Oh yeah. Well maybe instead of being disembodied flesh and blood it's more like mini-Jesus. You know, a grasshopper-sized version of Jesus experiencing the human condition in our stomachs?
[Kind of like Jonah in the whale.]
Him (slightly unsettled): Uh... yeah. I think that's more like the way Catholics think about it.
Me: Oh. Well then that does make sense.
For whatever reason I was comforted by the idea of mini-Jesus. Communion wasn't awful carnage disguised as bread and wine and there was a theological reason for it rather than just believing because that's what Catholics believe. When I read the Diary of St. Maria Faustina Kowalska (my first favorite saint!) I found that she had a profound love of the Eucharist (Communion) and she would refer to the wafer as the "little Jesus". Just like my mini-Jesus!! She would go visit Jesus in the consecrated hosts in the tabernacle (which is where the mini-Jesuses get stored) and she would have conversations with him.
This is why Scott Hahn says, in Rome Sweet Home, that Catholicism is either true or diabolical. [Unless there is no such thing as God, in which case getting worked up over what's true or isn't is about as silly as getting worked up about the weekly horoscope or Feng Shui.] Catholics literally worship a wafer (and wine) because they believe it is Jesus. If that wafer is NOT Jesus then they are simply worshipping a wafer. And that is just plain wrong. The God of the Bible makes it pretty clear that it's not cool to worship anything that isn't Him.
So my sort of Catholic ex-boyfriend was right after all, this is one of the most important differences. Although since then I have read (I don't remember where--so yeah, from a very reliable source) that believing Communion is symbolic is a relatively new thing, apparently Martin Luther believed in the physical presence of Christ in the Eucharist.
While I fixated on the gross out factor of flesh in the Eucharist, Jen (the Atheist-to-Catholic convert at the Conversion Diary), in her post called The God Who Becomes Dust, fixated on why God would choose something as lame as bread and wine as his vessel. She makes a funny point that maybe it's a lack of humility to think that bread and wine aren't glamorous enough to host God. For example, if God really is infinite and omnipotent and omni-everything-else then He may measure about a gazillion on the awesomeness scale while bread may register as 20 awesomeness units and humans 5,000. In that case, the difference in awesomeness between bread and humans is basically negligible.