There's the problem - Turkey is afraid the Iraq Kurds and the Syrian Kurds are going to join to form an autonomous state on their border. I think that's what Operation Euphrates Shield was about - keeping the Kurds out of a buffer zone. OTOH, the only reliable fighters the US can tap are the Kurds. But part of that problem is, the Kurds want to displace the Christians. Killing Isis is good, tho.
That seems far from being an absolute; there have been some incidences of strife between Kurds and Christians but overall, cooperation. The Assyrian (Christians) news website is worth exploring.