Faith: faith
fāTH/Submit
noun
1.
complete trust or confidence in someone or something.
"this restores one's faith in politicians"
synonyms: trust, belief, confidence, conviction; More
2.
strong belief in God or in the doctrines of a religion, based on spiritual apprehension rather than proof.
synonyms: religion, church, sect, denomination, (religious) persuasion, (religious) belief, ideology, creed, teaching, doctrine
"she gave her life for her faith"

Atheism: a·the·ism
ˈāTHēˌizəm/Submit
noun
disbelief or lack of belief in the existence of God or gods.
synonyms: nonbelief, disbelief, unbelief, irreligion, skepticism, doubt, agnosticism; nihilism
"atheism was not freely discussed in his community"

Agnostic: ag·nos·tic
aɡˈnästik/Submit
noun
1.
a person who believes that nothing is known or can be known of the existence or nature of God or of anything beyond material phenomena; a person who claims neither faith nor disbelief in God.
synonyms: skeptic, doubter, doubting Thomas, cynic; More
adjective
1.
relating to agnostics or agnosticism.
synonyms: skeptic, doubter, doubting Thomas, cynic; More

Nihilism: ni·hil·ism
ˈnīəˌlizəm,ˈnēəˌlizəm/Submit
noun
the rejection of all religious and moral principles, often in the belief that life is meaningless.
synonyms: skepticism, negativity, cynicism, pessimism; More
PHILOSOPHY
extreme skepticism maintaining that nothing in the world has a real existence.
historical
the doctrine of an extreme Russian revolutionary party c. 1900, which found nothing to approve of in the established social order.

I posted these definitions from the Google Dictionary because many here (all believers) don't know what they are or mean. Believers have some sort of odd belief that Atheism is a religion, that it is faith based, that it is even satanism. Also, people that are not atheist think that atheist act outside the norm of society, that they have no morals, no values, no ethics. Just the opposite is true. I know that this post won't do much because I really need to shake every single believer before they get it, but for the people on this forum that are believers and are here now you can learn that your assumptions are incorrect.
Also, atheism is a personal thing and very different to each individual. It isn't and never has been an organization. Atheists are as different from each other as any individual is. So don't assume that just because a person is an atheist that they fit a stereotype that YOU believe them to be.