There is little which precludes a Wiccan from also being a Christian and adhering to the values of Christianity.  Indeed many of the ancient values of Christianity were drawn from pagan sources.

We can see examples of this in the celebration of Easter in Christianity which was a pagan festival to the fertility goddess Oestra. That is why we use the pagan symbolism of the Easter egg, a simple fertility symbol.

Similarly, Christmas was a pagan mid-winter festival which celebrated the Winter god as he rode across the sky in his sledge drawn by a team of eight legged horses, later changed to a team of reindeers.

The quarter day and Christian festival of Candlemas is the pagan Festival of Light. And so, one could continue.

Most Wiccans seek only to pursue happiness as do most Christians. In that very human wish do Wiccans and Christians share so much that is true and good.