So my parents won't let me be Wiccan, and it seems that no matter how hard I try to reason with them, I can't get them to understand that paganism, wiccan, and other classes of paganism have nothing to do with the devil and his spawn. I enjoy being what and who I am, and I think being Wiccan allows me to be myself. However, remaining inside the broom closet was not one of my plans.
I'm still in high school, and I was born Catholic, raised Lutheran, and now Wiccan. What should I tell my parents to let them know I won't take "no" for an answer?
If you are still living under your parents' roof and they are paying for your care then any reputable Wiccan that I know would tell you to respect your parents' wishes at this time. There will be plenty of opportunity once you are of legal age and on your own to practice whatever religion you choose. Wicca will still be around and waiting for you.
In the meantime, there are many things that you can study that will stand you in good stead later but aren't specifically about Wicca. Study world religions, ancient cultures, herbalism, theology, ethics, etc. All of these are things anyone including Wiccans should be familiar with.
Of course no one, including your parents, can tell you what to believe about your religious choice. You can continue believing that Wicca is right for you. But you don't have to argue with your parents about it, you don't have to say anything to anyone about your beliefs. And you don't have to practice in your parents' home.
It sounds like you've explored all of the reasonable courses of action, and unfortunately have not seen a positive result. If they wont respond to reason, then I would suggest that you state your claim of being a Wiccan, let them know that this is the spiritual path that your are exploring, and tell them that if they ever would like to learn more about your path, then you would be more than happy to educate them. And leave it at that. If it turns into an argument, walk away, as clearly there is nothing that can be done to change their minds and it will only be detrimental to your relationship with them.
At this point, continue practicing as you wish, though you may have to stay in the broom closet or be "sneaky" to avoid confrontation - which is perfectly reasonable. When I was in your position I had to keep my practices a secret, and I had the maturity to understand that it was better that way. Its better to practice in secret then wage war with your parents over religious beliefs.
Some people are going to recommend that you "find the paganism" in Christianity, or study the bible because its good to have religious awareness, or even say to give in and allow your parents to choose your religious beliefs while under their care. While each of these options has its benefits, they also have their cons. I fully believe that you should stay with your path, and not be pushed into a spirituality that you don't connect with, but choose whatever course of action feels right for you.
I understand what you're going through, so if you have any questions or want to talk, you are free to send me a message. Also, this is a link to a guide I've written for people in the Broom Closet. It's not complete, but it should still offer some valuable insight:
Legally, your parents have the final say of what religion you practice until you are 18 (or until you are an independent).
Being in the Broom Closet myself, I understand the difficulty (although I am not a practicing Wiccan, just a witch). If they won't allow you to practice, you can do other things that will help you when you are able to practice freely. Like reading. Read books about Wicca, withcraft, crystals, gardening, herbs, pagan religions, cultures, ect. Compile resources. You can make yourself ready to practice without actually breaking your parent's rules.