I know how you feel, we of the Wicca are in early days, many many people still think we are satanic, others will think it's bad your not Christian.
Many people think Wicca is the religion of all Witches, as you seem to...it isn't. See here, it's initiatory.. http://www.paganfed.org/pagan-wicca.shtml
First thing is to get them away from the idea that we Witches are Satanic.
Emphasize we are of dual deity, God and Goddess as was the case before Christianity, Islam et al, perhaps you can obtain a professionally prepared document for them to read on what we are and what we are not. The Pagan Federation here in Britain produced a very good one that impressed members of my family. you could show this webpage by them on the topic of Paganism, which all Witches are....
http://www.paganfed.org/paganism.shtml