I was raised Christian, and have been trying to study Wicca and Paganism. For Christians, there is the Bible and the Ten Commandments to tell them what is right and what is wrong. Wicca doesn't have anything like that, so how do Pagans and Wiccans know what is moral and what is not?
Well, first of all, you've got to understand that morality is a fairly subjective thing. What is moral to one person may not be necessarily moral to another, regardless of faith or religious upbringing. That having been said, let's look at it this way. Is the only reason a Christian doesn’t kill is because the Ten Commandments prohibit it? If there were no such thing as the Ten Commandments, would you -- as a Christian -- think it was okay to kill?
Probably not, right?
And that's because our perception of right and wrong is based on a number of different things instead of just a list of rules. It's based on our personal experience, our empathy for other people, our upbringing -- not just religious, either -- and capacity for reasonable thought. In other words, I know it's wrong to steal because (a) I don't like to be stolen from, (b) I know it would hurt someone else if I stole from them, (c) my parents taught me not to steal and (d) it makes no sense for me to take something that does not belong to me. This is a fairly simplified explanation, but there you have it.
In some traditions of Wicca, practitioners follow what's known as the Rule of Three, which basically says that whatever you give out -- good or bad -- will come back to your threefold. While there are some variations on the interpretation of this concept, most Pagans and Wiccans agree that it's a useful guideline to have -- in other words, think before you act, because our words and deeds have consequences on many different levels.
There's also the Wiccan Rede, which is followed by some practitioners of Wicca. Unfortunately, many people forget that this beautiful piece of poetry consists of more than just the last line, An' it harm none, do as you will.
It's also important to remember that not all Pagans are Wiccans. The phrase "Harm none" has become a catchphrase for many people in some modern Pagan traditions, but again, it is not followed by all. However, even in the absence of the "Harm none" guidelines, every Pagan path has some structure or set of mandates -- whether formal or informal -- delineates what is acceptable behavior and what is not.
Ultimately, the difference between right and wrong -- and in which way one should act -- must be determined by the individual. There are plenty of people who belong to religions that have a list of rules, and yet we see examples of these rules being broken on a daily basis. For Pagans and Wiccans, just like for everyone else, it's a matter of thinking about the consequences of our actions, and knowing how to act based upon a combination of things, rather than just someone saying "Don't do this because there's a rule that says you can't do it."