Syncretism is "the attempt or tendency to combine or reconcile differing beliefs". It is a particularly relevant issue as western society becomes more pluralistic and less homogenous, so that we find ourselves more frequently encountering differing beliefs. Yet to some extent, Christians have been facing syncretism for millenia.

Conservative Christians often condemn syncretism for allowing pagan elements to taint pure Christianity. Especially it arises in accusatory form when Christians worship using non-conformant images or appellations for God, as in this article titled "The Sin of Syncretism": http://www.pbc.org/dp/goins/4390.html

Other Christians see that good can come from syncretism provided that the truth of the gospel is preserved. As a Celtic Christian -- indeed a Mac Ghille Eothain -- and with Celtic Christianity being the rootstock of the original pre-Roman Anglican church, I happen to think the syncretism that allowed Christianity to thrive in Celtic spirituality without the destructive loss of our culture, was a very good thing. Apparently in apologetical circles the term "contextualization" is now being used for 'good syncretism'. Here's some links I've found:

http://www.nativeamericanconcern.com/id34.htm
http://mb-soft.com/believe/txc/syncreti.htm
http://www.roxborogh.com/syncretism.htmhttp://www.pbc.org/dp/goins/4390.html