| Atheism |
There are a lot of misconceptions about what it means to be an atheist. Some people (disparagingly) call atheism a "religion," as much a matter of faith as believing in a deity. Others equate atheism with a conscious rejection of God. Particularly among devout monotheists (Christians, Jews, and Muslims), there is a tendency to look down upon atheists as having rebelled against God, embraced "evil," and/or adopted a completely amoral worldview.
All of these assumptions are false, except perhaps the first one, regarding faith . . . and that depends on the specific views of the atheist.
First of all, let's define our terms. These are not labels I made up myself, but established theological definitions.
(If you want more detailed readings on atheism, obviously there are plenty of resources. Here is a complete introductory essay at The Secular Web, which is one of the biggest atheist resources on the 'net. Below I give only a short summary, and I recommend you click the above link if you want a fuller discussion of the various degrees of atheism and agnosticism, and the philosophical questions surrounding them.)
I dislike these terms myself, frankly; "weak" atheism seems to imply a lack of conviction, someone who is uncertain about his disbelief. This is not what it means, of course, but these are the terms in use.
A strong atheist is one who actively denies the existence of God. He does not merely disbelieve in God, but affirms the premise that there is no God. A case can be made for calling strong atheism a form of faith, since strong atheists, in effect, have "faith" (meaning they accept something as true without proof) that there is no God. The most vehement strong atheists are the crusaders, the Madalyn Murray O'Hairs who campaign against religion.
The biggest problem with strong atheism is the conundrum of "proving a negative"; how do you prove that God doesn't exist? Of course, it is logically impossible to do so, but the argument isn't that simple. Strong atheists will point out, for example, that they don't necessarily assert that there are no gods (how does one define "god," after all?), but that the particulars of any entity known as God and worshipped by any human religion can be disproven, or at least shown to be highly illogical. A simpler argument is to point out that one cannot prove that invisible pink unicorns don't float over your bed while you sleep at night, yet the fact that numerous absurd premises can't be absolutely disproven doesn't mean that one is basing disbelief of them on mere "faith."
A weak atheist does not assert for a fact that there is no God. Instead, a weak atheist simply does not believe in God. If you are confused as to the difference, I'll refer you again to the introductory essay on the Secular Web. I'll put it succinctly here as follows: lack of belief in something does not mean accepting as a given (or "on faith") that that thing does not exist. For example, I do not believe that ghosts exist. I have never seen evidence of their existence, and I find the concept irrational because it does not fit what I know about the universe. Based on the available evidence, I conclude that the existence of ghosts is unlikely, and therefore will remain a disbeliever until I actually meet one. But I won't state for a fact that ghosts don't exist; perhaps they do, and either I have not been exposed to the right evidence, or else what I know about the universe is wrong. I can't absolutely rule those possibilities out. But I'm not agnostic (see below) about the existence of ghosts; I don't merely doubt their existence. I do not believe in them.
Being a weak atheist, my disbelief in God is similar; I don't state for a fact that there is no God, and I accept that evidence I have yet to encounter could change my mind. However, lacking any such evidence, I find the concept of God irrational and see no reason to believe that such an entity exists.
Many people who call themselves agnostics are in fact weak atheists, and vice versa, adding to the confusion about what it means to be an atheist.
An agnostic is, most literally, one who does not know, and knows he does not know. Someone who answers the question "Do you believe in God?" with "I don't know" is an agnostic. (A strong atheist would answer with "There is no God," and a weak atheist would answer with "No.")
However, there are degrees of agnosticism as well. The original definition was someone who considers the question of God's existence to be essentially unknowable; we humans, lacking the ability to perceive gods, can never be sure whether or not God exists. Thus, an agnostic would claim that both theists and atheists are adhering to a belief without foundation. This sort of agnostic is known as a "strict agnostic," or sometimes a "strong agnostic."
But some agnostics don't consider God unknowable. They have a clear idea of what evidence would convince them that God exists, and they can conceive of believing in God, given that evidence, but having not yet seen any such evidence, remain unconvinced either way. These agnostics are "empirical agnostics," or sometimes "weak agnostics."
Historically, "freethinker" was often a euphemism for an atheist, in eras when it was detrimental to one's career and social standing to openly proclaim disbelief in God. Nowadays, freethinkers are people dedicated to intellectual inquiry. A freethinker avoids making assumptions, and endeavors to investigate all premises before accepting them as true.
Most freethinkers are atheists or agnostics. The term is often misused, since there is a tendency among some non-believers to assume all atheists and agnostics are "freethinkers," while no religious believer can be one. Because of the close association between the freethinking philosophy and atheism, it can be an inflammatory term. When a non-believer proclaims himself a "freethinker" before religious believers, the implication often perceived by the believers, whether or not the freethinker intended it, is "You are not free-thinkers . . . i.e., you are mindless sheep."
I do consider myself a freethinker, but I don't usually use that term to describe myself.
Some people confuse "skeptic" with "cynic," and think that skeptics spend all their time trying to bash new ideas while denying others' beliefs. No doubt, some skeptics are cynics, and vice versa, but that's not what skepticism is about.
A skeptic does not believe in things which have not been tested. A true skeptic has an open mind; if someone claims to have psychic powers, or boasts of a new "alternative medicine" treatment, the skeptic does not dismiss the claim and say "What nonsense!" He says: "Prove it to me. I'd like to see a demonstration."
Skepticism means critically examining all claims and not accepting anything as a fact unless it is supported with evidence. The scientific method is regarded as the best tool with which to investigate the universe. Only phenomena that can be repeated under scientific scrutiny have scientific validity. (Some phenomena are inherently outside the domain of science and cannot be tested -- faith in God, for example. A skeptic might not believe in God, but won't claim he can "disprove" God, only that there is no evidence for such a being.)
A skeptic doesn't have to be an atheist (some people do believe in God or other supernatural phenomena based purely on faith, and admit that they have no evidence or any other rational reason to believe), but most skeptics are atheists, or at least agnostics.
More or less synonymous with skeptic or freethinker. A rationalist believes that all the answers to the universe can be deduced by reason -- which doesn't mean that we know everything, or ever will, but that everything meaningful has a natural explanation. Rationalism rejects faith or supernaturalism as an explanation or solution to any problem.
Also called "secular humanists." Humanism is the belief that only humans can give meaning to their own lives. It is a naturalist philosophy that rejects gods or other supernatural beings as a source of meaning or morality. Humanists have an ethical philosophy based on rationalist ideals, and advocate a responsible, humane lifestyle. Thus, humanism might be considered a "religion" for atheists, fulfilling much the same function that traditional religions do for theists. Theoretically, one could be a humanist without being an atheist, but one would have to believe in God while also believing that God has no relevance or responsibility in our lives, which is contrary to most theistic beliefs.