Periyar was a rationalist. There are many problems the world over today due to religious fundamentalism, especially the intolerance of the followers of Semitic religions (Judaism, Christianity and Islam). The religions were created by vested interets to hoodwink the gullible masses. Hinduism is not a religion in its narrow sense. It is a conglomeration of various beliefs and eve non-beliefs (atheists existed even in Vedic periods and were known as "Charvakas").
Since the Brahmins were behaving as if they are the whole-sale dealers of spiritualism, Periyar was against them. Their caste superiority coupled to the natural cunningness of Tambrams became a deadly combination!