Hi, E'Unique! (hope I remembered the spelling right) by: Swedishfairy
My answer is yes to your questions. Anyone can practice witchcraft.
I am assuming you mean the Judeo-Christian God when you say God. Many witches (or witchcraft practicioners) believe that all the gods are one. There are so many similar stories about the gods. If you were to compare the stories about the Norse god, Odin (sometimes called Woden), to Horus, to Jesus, there are similar stories. There are differences as well. There are also different ideologies that are connected with different gods and belief systems. You'd need to work that out for yourself.
There may be Christians that disagree with me, because there are several references in the Bible about witchcraft being detestible and that witches should be killed. So I suppose what that means for you, is you are the ultimate decider of your belief system. And, do you take in *everything* that belief system says, or do you mix and match? Lots of witches/witchcraft practicioners mix and match and call themselves 'eclectic.'
As to your last question as I remember, what witchcraft can do, I can only share my own experiences.
The Celtic Sabbats (and other pagan ceremonies) can hold a lot of meaning and are very therapeutic. Samhain, for example, is a time when we show respect to those who have passed on, and some try to communicate with them. It took me a long time to be able to face my grief and celebrate that holiday. The symbolism in the holidays strikes a chord to the very center of our being; it's deeply personal.
I'm guessing that's not really what you meant, however- maybe you are speaking of spells and what they can do. Really, the better question is, what can *you* do- not witchcraft, not the spell, not the ritual. Those are tools that help us do things psychically and work along with the powers that be. Some of us (maybe all of us- I believe all of us) have the potential to be psychic, and as for myself, energy workings (which are like a pagan form of prayer) and speaking with my guides have helped me make better decisions, and help others. I've also had forewarning of some things.
I would suggest that you learn to meditate (and if you have questions about this, just ask and I can share what I know), meet your spirit guide(s), and go from there.