South Caucasus, conquered by Mongols and controlled by Ilkhanids, was the homeland of Bagrationi administration. The governors in this region, except Arran and Karabakh, were under the supreme ruling command of Bagrationi. So there had been some political affairs between the governors and Ilkhanids. Seeking a reasonable explanation and analysis regarding South Caucasus development from religious point of view, this article is to answer this question: what was the impact of Ilkhanid’s foreign affairs, namely religious policy, on Christians in this region.The findings, based on the documents and library resources, confirm the significance of south Caucasus for the Ilkhanids either as a strategic territory or for the rival claim of Golden Horde in the region. The non Muslim Ilkhanids made a great effort to not only give advantage to the Christians to prevent them from coalition with the Golden Horde, also to take advantage from Christians hostility against Muslims to win the Golden Horde and Mamluks at the same time. On the other hand, the Christians of South Caucasus were looking forward to misusing the ideological differences between non Muslim Ilkhanids and Mulims for the sake of Christianity transcendence. Although Ilkhanids’ conversion to Islam relatively changed the pattern of religious policy against Christians, the general policy of the converted Ilkhanids remained unchanged towards non Muslim Ilkhanids. This was regarding the utilization of their military force and also to maintain the land as a strategic retaining territory against the Golden Horde.