Webster’s Revised Unabridged Dictionary · 1913
Atheistic
A′the·is′tic, A′the·is′tic·al, a. 1. Pertaining to, implying, or containing, atheism; — applied to things; as, atheistic doctrines, opinions, or books.
Atheistical explications of natural effects. Barrow.
2. Disbelieving the existence of a God; impious; godless; — applied to persons; as, an atheistic writer. — A′the·is′tic·al·ly, adv. — A′the·is′tic·al·ness, n.