atheist: one who believes that there is no deity

atheism:

1 archaic : UNGODLINESS, WICKEDNESS
2 a : a disbelief in the existence of deity b : the doctrine that there is no deity

disbelief:  the act of disbelieving : mental rejection of something as untrue

disbelieve:

transitive senses : to hold not worthy of belief : not believe
intransitive senses : to withhold or reject belief
 

agnostic: a person who holds the view that any ultimate reality (as God) is unknown and prob. unknowable; broadly : one who is not committed to believing in either the existence or the nonexistence of God or a god

Atheist:
1. One who denies or disbelieves the existence of a God.
2. One who practically denies the existence of a God by disregard of moral obligation to Him; a godless man.
    B. attrib. as adj. Atheistic, impious.
 

[Note: The last word usage example for sense #1 is:  1876 GLADSTONE in Contemp. Rev. June 22 By the Atheist I understand the man who not only holds off, like the sceptic, from the affirmative, but who drives himself, or is driven, to the negative assertion in regard to the whole Unseen, or to the existence of God.]

Atheism:
Disbelief in, or denial of, the existence of a God. Also, Disregard of duty to God, godlessness (practical atheism).

Agnostic:
A. n. One who holds that the existence of anything beyond and behind material phenomena is unknown and (so far as can be judged) unknowable, and especially that a First Cause and an unseen world are subjects of which we know nothing.
[Suggested by Prof. Huxley at a party held previous to the formation of the now defunct Metaphysical Society, at Mr. James Knowles's house on Clapham Common, one evening in 1869, in my hearing. He took it from St. Paul's mention of the altar to ‘the Unknown God.’ R. H. HUTTON in letter 13 Mar. 1881.]

B. adj. Of or pertaining to agnostics or their theory.
 

Disbelieve:
1. trans. Not to believe or credit; to refuse credence to:

    a. a statement or (alleged) fact: To reject the truth or reality of. (With simple obj. or obj. clause.)
    b. a person in making a statement.
2. absol. or intr.
3. intr. with in: Not to believe in; to have no faith in: cf. BELIEVE 1, 3.

atheist: One who disbelieves or denies the existence of God or gods.

atheism:

1a. Disbelief in or denial of the existence of God or gods. b. The doctrine that there is no God or gods.

2. Godlessness; immorality.

ETYMOLOGY: French athéisme, from athée, atheist, from Greek atheos, godless : a-, without; see a–1 + theos, god; see dhs- in Appendix I.

disbelief: Refusal or reluctance to believe.
 

denial:

1. A refusal to comply with or satisfy a request.

2a. A refusal to grant the truth of a statement or allegation; a contradiction. b. Law The opposing by a defendant of an allegation of the plaintiff.

3a. A refusal to accept or believe something, such as a doctrine or belief. b. Psychology An unconscious defense mechanism characterized by refusal to acknowledge painful realities, thoughts, or feelings.

4. The act of disowning or disavowing; repudiation.

5. Abstinence; self-denial.

agnostic:

NOUN:

1a. One who believes that it is impossible to know whether there is a God. b. One who is skeptical about the existence of God but does not profess true atheism.

2. One who is doubtful or noncommittal about something.

ADJECTIVE:

1. Relating to or being an agnostic.

2. Doubtful or noncommittal: “Though I am agnostic on what terms to use, I have no doubt that human infants come with an enormous ‘acquisitiveness’ for discovering patterns” (William H. Calvin, New York Times Book Review August 10, 1997).

WORD HISTORY: An agnostic does not deny the existence of God and heaven but holds that one cannot know for certain whether or not they exist. The term agnostic was fittingly coined by the 19th-century British scientist Thomas H. Huxley, who believed that only material phenomena were objects of exact knowledge. He made up the word from the prefix a–, meaning “without, not,” as in amoral, and the noun Gnostic. Gnostic is related to the Greek word gnsis, “knowledge,” which was used by early Christian writers to mean “higher, esoteric knowledge of spiritual things”; hence, Gnostic referred to those with such knowledge. In coining the term agnostic, Huxley was considering as “Gnostics” a group of his fellow intellectuals—“ists,” as he called them—who had eagerly embraced various doctrines or theories that explained the world to their satisfaction. Because he was a “man without a rag of a label to cover himself with,” Huxley coined the term agnostic for himself, its first published use being in 1870.

atheist:

1. One who disbelieves or denies the existence of a God, or supreme intelligent Being.
2. A godless person. [Obs.] Syn. -- Infidel; unbeliever. See Infidel.
 

atheism:
1. The disbelief or denial of the existence of a God, or supreme intelligent Being.
2. Godlessness.
 

disbelief:

The act of disbelieving;; a state of the mind in which one is fully persuaded that an opinion, assertion, or doctrine is not true; refusal of assent, credit, or credence; denial of belief.

Syn. -- Distrust; unbelief; incredulity; doubt; skepticism. -- Disbelief, Unbelief. Unbelief is a mere failure to admit; disbelief is a positive rejection. One may be an unbeliever in Christianity from ignorance or want of inquiry; a unbeliever has the proofs before him, and incurs the guilt of setting them aside. Unbelief is usually open to conviction; disbelief is already convinced as to the falsity of that which it rejects. Men often tell a story in such a manner that we regard everything they say with unbelief. Familiarity with the worst parts of human nature often leads us into a disbelief in many good qualities which really exist among men.

disbelieve:

Not to believe; to refuse belief or credence to; to hold not to be true or actual.
 

deny:

(transitive verb)
1. To declare not to be true; to gainsay; to contradict; -- opposed to affirm, allow, or admit. &hand; We deny what another says, or we deny the truth of an assertion, the force of it, or the assertion itself.
2. To refuse (to do something or to accept something); to reject; to decline; to renounce. [Obs.]
3. To refuse to grant; to withhold; to refuse to gratify or yield to; as, to deny a request.
4. To disclaim connection with, responsibility for, and the like; to refuse to acknowledge; to disown; to abjure; to disavow.

(intransitive verb) To answer in negative; to declare an assertion not to be true.

denial:

1. The act of gainsaying, refusing, or disowning; negation; -- the contrary of affirmation.
2. A refusal to admit the truth of a statement, charge, imputation, etc.; assertion of the untruth of a thing stated or maintained; a contradiction.
3. A refusal to grant; rejection of a request.
4. A refusal to acknowledge; disclaimer of connection with; disavowal; -- the contrary of confession; as, the denial of a fault charged on one; a denial of God. Denial of one's self, a declining of some gratification; restraint of one's appetites or propensities; self-denial.
 

agnostic:

(noun) One who professes ignorance, or denies that we have any knowledge, save of phenomena; one who supports agnosticism, neither affirming nor denying the existence of a personal Deity, a future life, etc.
 

agnosticism:

That doctrine which, professing ignorance, neither asserts nor denies. Specifically: (Theol.) The doctrine that the existence of a personal Deity, an unseen world, etc., can be neither proved nor disproved, because of the necessary limits of the human mind (as sometimes charged upon Hamilton and Mansel), or because of the insufficiency of the evidence furnished by physical and physical data, to warrant a positive conclusion (as taught by the school of Herbert Spencer); -- opposed alike dogmatic skepticism and to dogmatic theism.

atheist: somebody who does not believe in God or deities

disbelief: the feeling of not believing or of not being able to believe somebody or something