%syncretist%

n. [ Cf. F. syncrétiste. ] One who attempts to unite principles or parties which are irreconcilably at variance; specifically (Eccl. Hist.), an adherent of George Calixtus and other Germans of the seventeenth century, who sought to unite or reconcile the Protestant sects with each other and with the Roman Catholics, and thus occasioned a long and violent controversy in the Lutheran church. [ 1913 Webster ]