Q. Can I be Christian and Wiccan?
A. My response is another question back to you: why would you want to be? Why try to mix 2 very different religions in the first place? I feel that many people are unable to drop the tenets of Christianity because it is so prevalent in today's Western society. It's difficult to turn your back on a religion that you have been immersed in all of your life. But if you are unsatisfied with Christianity, then let it go.
Ok, enough of my own opinions. In fact, you cannot truly blend Wicca and Christianity. Wicca has a dual Divinity (God and Goddess) whereas Christianity clearly has a single God. This single point alone is enough to put the two religions at odds with each other. You could bend the rules a little, and proclaim Mary to be a Goddess. But when you start to bend rules, you change the nature of the religion.
Worshipping Mary as a Goddess is perfectly acceptable (in my Wiccan mind) but is it truly Christian? If you choose to do so, you should realize that 'Christian' is no longer a label you should use for yourself.
On the other hand, if you are interested in Christianity and witchcraft, that is another kettle of fish. As I have mentioned in another FAQ entry, Wicca and witchcraft are not the same thing. Since witchcraft has no religious overtones, it is easier to blend with other beliefs. Unfortunately, Christianity still has many restrictions against sorcery, witchcraft, and divination. The one most people are familiar with is Exodus 22:18 (Thou shalt not suffer a witch to live). Again, if you wish to ignore certain verses in order to fit your witchcraft practices into your Christianity, you may want to rethink calling yourself a Christian.
Bottom line, creating your own personal path from 2 (or more) different religions is perfectly fine. But you need to realize that you should not still refer to your path by its original names.