Atheists, I need your help...am I a "fraudulent atheist"?

Ok, to make a long story short, I have been having a debate with a Christian friend of mine about whether I have the right to call myself an atheist. I was born into the Roman Catholic culture...baptized, confirmed, taught religion and all that stuff. I've not held a single religious belief for over fifteen years...I believe in just death after life and have distanced myself from organized religion...but my friend claims that because I have been "sealed" into the church since my baptism and that I actually should hold the term "nonpracticing Christian" instead of atheist. In accordance, he states that I have to write a letter to the church or pope asking for permission to leave the church...only then will I have the right to call myself an atheist...is this true or false???