ok why do you want to be goth? if it is because you want to fit in please stop. if not tell your parents that you want to be different then everyone else and you like the goth lifestyle if this is true. I also suggest to make a list of good things about Goths and the misunderstood things because some parents have heard that all Goths are satanic and are witches and worse things. for the list you may add some negatives but there is only a few and if you can't think of any that is good. one more thing how old are you? I am goth and had to go through this too. goth people are not bad or wicked. I am also Christian
I suggest you try explaining these to them slowly while not expecting a good reaction from them. Let it be a gradual process hence giving them enough time to come to terms with it. Alternatively you can get a close relative to help you.
Goths wear black and like music from the 80's, right? Am I missing something. How does this define who you are? Isn't it just a fraction of your whole self? Maybe I'm too old to understand your question. What do you want your parents to do that they're not doing?
"This type of behavior is a direct threat to the upright morals and values of the era and will not be afforded a spot in the basement bomb shelter when the REDS drop the bomb". WHAT THE HECK WERE THEY TALKING ABOUT? Rock and Roll, sweetheart in the 50's. My point is, there will always be a generation gap; in the past half century and the next. Just wear your clothes and listen to your music and act the same way you always did with your parents. It's not as big as you are making it.