The notion that bigot is primarily synonymous with "racist" is a modern change; traditionally it was just concerned with intolerance of conflicting ideas. I think it was over the political debate about segregation that the idea bigotry transferred to racial attitudes.
(obsolete) One who is overly pious in matters of religion, often hypocritically or else superstitiously so.
the eighteenth century probably dates back to the more obsolete sense of the word
1820 Charles Robert Maturin "Donna Clara was a woman of a cold and grave temper, with all the solemnity of a Spaniard, and all the austerity of a bigot."