One note to add to Aaron's statement about creeds. Probably the most
widely accepted summary of Christian belief is the Apostle's creed,
which developed between the third and sixth centuries, and is accepted
by the Eastern Orthodox, Roman Catholic, and most Protestant churches.
You can find the original Greek and Latin texts, along with English and
French translations, at <http://www.creeds.net/ancient/apostles.htm> It
explicitly mentions the virgin birth and resurection. It may be the
closest thing that exists to a widely accepted definition of Christianity.