There are definitely mentions of feuds over religious issues aside from the activities of the followers of R'hllor. The earliest example is the war between the Children of the Forest and the First Men, which began after the First Men cut down the sacred weirwood trees. In another example, The World Of Ice and Fire describes an outright war between the Faith Militant and the early Targaryen kings over their customs of polygamy and incest.

There are definitely mentions of feuds over religious issues aside from the activities of the followers of R'hllor. The earliest example is the war between the Children of the Forest and the First Men, which began after the First Men cut down the sacred weirwood trees. In another example, The World Of Ice and Fire describes an outright war between the Faith Militant and the early Targaryen kings over their customs of polygamy and incest.