The context is in Book VII of the Samuel William Orson translation:
[Ignacio Emanuel de Altuna] never in his life asked any person his opinion in matters of religion. It was not of the least consequence to him whether his friend was a Jew, a Protestant, a Turk, a Bigot, or an Atheist, provided he was an honest man.
(In case anyone who stumbles upon this thread is wondering, “Turk” means “Muslim” in context.)
A bigot, in French, is a person who is exceedingly religious, or hypocritically religious. This was already the definition found in Furetière's dictionary of 1690, and it hasn't changed since. The meaning in English has a wider scope: in French it is strictly used for religious people. It's not very nice, and never used positively, but at least a bigot (in the first meaning) can be honest. It's a person who's always in church, or cannot stop talking about religion, or forces their religious views upon other people. It's used here as a somehow derisive antonym of atheist.
Que son ami fût juif, protestant, Turc, bigot, athée, peu lui importait, pourvu qu’il fût honnête homme.
I'm not sure why the translation used an uppercase initial: it's only a common noun, not that of a nationality or religious affiliation.