Q: Can you be a Pagan and a Christian?
A: Yes. Such people may call themselves Christo-Pagans, Mystic Christians, or other names reflecting their dual heritage. Angel Wicca is another popular example. Some Afro-Caribbean religions like Santeria combine Pagan and Christian elements too. You can blend together aspects from many different religions according to what feels right to you; many people do this. In your explorations you might meet a "Jewitch" studying Judaism and Witchcraft, or a "Pagan Sufi" studying Paganism and the Sufi branch of Islam, or just about any other combination you can imagine.
— Elizabeth Barrette, lives in central Illinois with lifepartner, in a large Victorian farmhouse with a yard frequented by wildlife. An avid wordsmith, she works as a writer and editor, doing poetry, articles, essays, reviews, interviews, short stories. She is a former editor of PanGaia magazine and has written several popular books published by Llewellyn including the popular 2012 Magical Almanac and Composing Magic and many more. She is a member of The Greenhaven Tradition, and Fieldhaven Coven in central Illinois.
Wikipedia gives this:
It is perhaps misleading even to say that there was such a religion as “paganism” at the beginning of [the Common Era] ... It might be less confusing to say that the pagans, before their competition with Christianity, had no religion at all in the sense in which that word is normally used today. They had no tradition of discourse about ritual or religious matters (apart from philosophical debate or antiquarian treatise), no organized system of beliefs to which they were asked to commit themselves, no authority-structure peculiar to the religious area, above all no commitment to a particular group of people or set of ideas other than their family and political context. If this is the right view of pagan life, it follows that we should look on paganism quite simply as a religion invented in the course of the second to third centuries AD, in competition and interaction with Christians, Jews and others.
—North 1992, 187—88, in Cameron, Alan G.; Long, Jacqueline; Sherry, Lee (1993). Barbarians and Politics at the Court of Arcadius. University of California Press.
Wikipedia gives this:
Paganism is a broad group of indigenous and historical polytheistic religious traditions—primarily those of cultures known to the classical world. In a wider sense, paganism has also been understood to include any non-Abrahamic, folk, or ethnic religion.
Contemporary or modern paganism, also known as neopaganism, is a group of new religious movements influenced by, or claiming to be derived from, the various historical pagan beliefs of pre-modern Europe.There is much more discussed on that site.