Analysis of information sources in references of the Wikipedia article "Atheism" in Simple English language version.
The true default position is neither theism nor atheism, but agnosticism … a claim to knowledge needs to be substantiated; ignorance need only be confessed.
Atheism and atheist are words formed from Greek roots and with Greek derivative endings. Nevertheless they are not Greek; their formation is not consonant with Greek usage. In Greek they said atheos and atheotēs; to these the English words ungodly and ungodliness correspond rather closely. In exactly the same way as ungodly, atheos was used as an expression of severe censure and moral condemnation; this use is an old one, and the oldest that can be traced. Not till later do we find it employed to denote a certain philosophical creed.
Old Greek word, not in LXX, only here in N.T. Atheists in the original sense of being without God and also in the sense of hostility to God from failure to worship him. See Paul's words in Ro 1:18–32.