How To Tell Mom and Dad You're Not Evil 

You're young, you're ambitious, and you've discovered Wicca. It's everything you've been searching for--it fills that spiritual gap in your life. Only problem is, you're under 18 and whatever mom and dad have to say about it is what goes. Ah the horrible archaic law that says teenagers should have no religious freedom. Even worse, some of you have parents that think you're on the path to evil! They're eventually going to wonder where you got this sudden interest in candles and incense. So, how do you explain to them that you're not out to sacrifice the neighbours' cat or burn down the house?

The first approach would be to sit them down and explain to them what you believe. Tell them that it is a nature-revering belief system, whose main rule is to respect all things. Explain to them that harming another living thing goes against Wiccan belief. Be sure they know that this does not change who you are, and you will not start wearing all black, you will not get piercings in odd places, you won't start sleeping all day and partying all night (or explain to them that doing that has nothing to do with Wicca).
If this doesn't sway them, and they think you're making it up, take them to one of the "Wicca for Parents" websites. Some of these sites are: 

http://www.glasstemple.com/basics/parents.htm

http://www.geocities.com/Heartland/1226/witch.html

Be sure to explain the Rede and the Threefold Law to your parents. Show them that Wiccans live by these Laws every day. You might want to explain your feelings about their religion (WITHOUT bashing it, mind you). Explain to them that you weren't satisfied with it for whatever reason, whether you didn't buy the idea of eternal damnation, or you weren't comfortable with a judgmental male God. Explain to them how Wicca makes you feel, how it makes you a better person and how it will affect you in the future (you know, the whole friendly tree-hugger type thing).

Along with this, there are things you shouldn't do. Don't tell them that their beliefs are stupid or inferior to your own. Don't shout or get angry with them. Remember, some parents were raised so firmly to believe in their faith that they dismiss any other path as the wrong one. Simply tell them you don't feel that way about it. Make sure they know that these beliefs make you feel happier, better about yourself, or better about the world than theirs could. You could even go as far as telling them you're uncomfortable with the idea of religion being chosen for you, and that you feel it's a personal decision. If they accuse Wicca of being Satanic, tell them that Wicca does not believe in an ultimate good or evil, and that Satan is a foreign concept to Wicca.

The main goal is to be mature about it, and give them references that reinforce the fact that Wicca is not evil or Satanic. Even if they don't agree with your beliefs, at least you have given them something to think about. They may not allow you to practice Wicca at home (at least, not in front of them), but if you are dedicated, they will see over time that you aren't sneaking off at night to kill small animals, and that you are becoming a better person.

Remember also that once you're 18 (in North America at least), you're free to believe whatever you wish, despite your parents' wishes (it's the law).