How can you leave your religion?
No matter how many times I say I’m not a catholic or that I’m atheist someone always says, and I’m sure its with a smirk, “ah but you were born a catholic.” Sorry I thought I was born a human.
I know in Germany you can divorce yourself from your religion on tax gorunds but how do I do it so it counts anywhere in the world? I’ve been told if you throw the eucharist around the church you can be thrown out but that seems slightly disrespectful and possible illegal.
Unless you’re a priest or bishop your options are limited to four. You can attack the Pope. You can procure or perform an abortion, although according to this site http://www.magi.com/~godfree/excom.html just contributing to groups like Planned Parenthood can get you axed, but they don’t actively seek you out. You can desecrate the sacred host (desecration of sacred places), though it isn’t reccommended, and last, and by far the easiest one, Apostasy, heresy, or schism. The church automaticly boots you if you can prove it applies to you:
(from the website noted above)
Here’s Cecil’s answer.
Arjuna34
For more information than you ever wanted to know about excommunication (104 kilobytes worth of text- a small book), the Catholic Encyclopedia has pretty much the official word on it here.
The problem you’re having is not with the processes of the Church, but with human nature. It’s your fellow humans who insist on labeling you; even if you do get excommunicted, you’ll just be an ex-Catholic. Blaspheming the Host won’t change your fellow human’s minds.
As for leaving the Church, once you’ve made up your mind, you’re done. It’s not like there’s a central office that requires you to fill out paperwork or something. And if you really want to screw with the Universe, go ahead and call yourself an atheist, then repent on your deathbed. That way, you’ve covered all your bets. 
As Guy Propski said, getting yourself excommunicated is only going to provoke the people who insist upon labeling you to change the label to “ex-Catholic.” Anyway, isn’t it a big ol’ waste of time and effort to attempt to achieve excommunication from an organization you don’t participate in and a deity you don’t believe in? It would probably be easier to just come up with a snappy response to the the labelers:
Smirky Idiot: “Well, you were born Catholic, weren’t you?”
You: “Yeah, I was. I was also born a baby. Now I am an adult. I was born a Catholic. Now I am an athiest.”
-or-
You: “No, I wasn’t. I never chose to become Catholic or Christian and as soon as I was old enough to deny being either I did so. I consider infant baptism to be a kind of spiritual molestation and refuse to consider it legitimate.”
Easier still would be to just ignore such idiocy. Some people were just born idiots and stayed that way. It’s kind of a waste of breath to argue with them.
I should say that I didn’t mean to insult anyone here with my second example above. It’s just that offensive snappy responses tend to work better than polite ones – at least if the objective is to shut the Smirky Idiot up. Sometimes, if you are really offensive (and I admit that my example is extremely offensive) the Smirky Idiot will stop speaking to you completely. Obviously, Extremely Offensive Snappy Responses should only be deployed upon people whom you don’t mind being permanantly estranged from.
Personally, I rarely use the Snappy Response – although I do enjoy making them up. My standard response to Smirky Idiots is a cold look and a colder shoulder.