What's your religion? That should have your answer. If you're Eclectic Wiccan, yes, you could worship both. If you're Christian and want to be Wiccan or follow witchcraft, it's a grey area really, do what feels right to you. While Wicca is flexible Christianity isn't. In the commandments, you can only worship 'God' so you couldn't worship Lupa. The bible also has some passages against magick/witchcraft and historically Christians and Pagans didn't get along very well. But, there are Christian Wiccans so it's possible.
If you want to cast spells but be Christian, you can, witchcraft and magick can be practiced by anyone. Basically do some soul searching and draw your own conclusions.