2 adverbs to describe how to atheists

But "th between two vowels, is generally flat in words purely English; as in gather, neither, whither: and sharp in words from the learned languages; as in atheist, ether, method"See W. Allen's Gram., p. 22.

Among themselves they were frankly atheists.

2 adverbs to describe how to  atheists  - Adverbs for  atheists