When one is talking about one's beliefs, the first order of business is dealing with God. It's pretty much agreed to all around that the answers to most of the other Big Questions are dependent on whether God exists and, if so, what God is like.
Definitions are important, of course. For the next while, I'll be using the term "God" as shorthand for any and every theistic construct, anything with the aroma of divinity, the least hint of transcending the material. This is simply a matter of convenience as we examine the non-theistic positions. I understand I am doing the non-theists a slight disservice, but I'm only going to deal with them in three big lumps: the atheist, the unconvinced, and the agnostic. I use "atheist" in the classic sense, that is, one who has a positive belief that there is no God. This position is sometimes called "strong atheism" to differentiate it from "weak atheism", which I refer to as "unconvinced". These last do not say that God does not exist, but that they simply have not encountered any convincing evidence of that existence. I use "agnostic" in a somewhat mushy way to cover all those who believe the question of God's existence is somewhat moot because we cannot answer the question of God's nature. Obviously, I personally reject all three positions. Considered together or separately, I find them to be afflicted with various philosophical and practical inconsistencies.
One thing all three positions have in common is that they reject all accounts of personal religious experience and all purported acts of supernatural revelation or intervention. More precisely, I should say that they reject the idea that any of these events are meaningful in establishing the existence or identity of God. While they often agree that the people involved are sincere, they are just as convinced that those people are sincerely wrong, having attributed intelligent purpose to events that can be more simply explained. Though the non-theists often say "simply", they really mean "naturally". If there is a non-zero possibility of an event occurring without divine action, then any non-divine explanation is automatically given priority, regardless of actual evidence. The non-theists will maintain that their position is based on the axioms of the scientific method, testable hypotheses, and Occam's Razor. In many instances, however, the only factor mitigating in favor of a completely mundane explanation is the non-theist's own commitment to mundanity. Indeed, the method by which they derive truth cannot be verified under its own terms. Science and reason are tools for finding truth, but they cannot in themselves show they are the way to all truth, or even the only way to some truth. They can barely manage to show that truth is a thing to be valued. To reject "unscientific" evidence regarding the existence and nature of God involves a personal choice and becomes, in the best sense of the term, an act of faith. This is a fundamental and, to my mind, fatal inconsistency.
Another point common to all three positions is an inconsistency in practice, if not in thought. Non-theists will often argue for their right to live as they please, their freedom to not worship, and the dangers of theism, without seeming to realize that these concepts are meaningless in the absence of an overarching moral/ethical agent to which we all must eventually answer. Unless one is accountable to God (remember my broad definition), there is no reason to respect another person's rights, freedom, health, emotions, or property where there is a clear personal advantage in not doing so. If the only material fact of existence is the fact of material existence, then no phenomena can be described as "right" or "wrong", "good" or "bad", "better" or "worse" in any absolute terms. Consider the following poem:
My love said, "We are just machines after all".
So I chained her to the wall for my future use,
And she cried.
Forgive me, I do not have the name of the author, and I'm not sure I've quoted it correctly, but the point of inconsistency remains. I've never found a non-theist who acted as if they really believed that people were nothing more than lucky pieces of matter. A non-theist cannot philosophically justify any moral pronouncement, yet every non-theist I've ever encountered keeps making them. I've heard and read statements to the effect that this world would be a much better place if all the religionists were gone. These statements are made by people who, I'm sure, are horrified by accounts of Stalin's and Mao's efforts to produce just such a world. People have written entire books "proving" that free will is illusory and, therefore, morality is nonexistent. These books always conclude that, in recognition of this, we should reform or eliminate various aspects of society, despite just having shown that the word "should" cannot be meaningfully applied to those efforts. If criminals cannot be held morally responsible for their crimes, no one can be held morally responsible for the way criminals are treated. If an organism has no fundamental right to exist, it cannot be considered wrong to end that existence. If one believes that concepts of autonomy and self-determination are meaningless, one cannot philosophically object to abuses of imaginary freedoms. In short, a truly consistent non-theist would be an extremely dangerous individual, capable of any act, free of any justification. Would anyone in their right mind truly want to live in a world that only contained such people, who are better called "animals", concerned only about their own pleasures and appetites? That we do not live in that world is evidence that God and morality are real or, at least, extremely useful fictions. In either case, efforts to remove them from society or counter their influence seem misguided.
As weak as the non-theist positions are in sum, they become weaker when considered individually. The least tenable position is that of strong atheism. While it may be possible to show that a particularly or peculiarly defined God cannot exist, it is not possible to show that God, in the broad sense, does not exist. Any being possessing that much knowledge about this material universe, let alone propositional, n-dimensional, or transcendental varieties of existence, would itself qualify for the title of God.
The agnostic view is only slightly better in that I find a partial truth in it, or at least a particle of truth. While I believe we can't know or understand everything about God, it seems a little silly to say that we can't really know anything. That statement seems to require a large amount of information about God that the statement says we can't ever have. In effect, agnostics are claiming to know more about the nature of God than theists.
Then there are the unconvinced, the so-called "weak" atheists. They do not believe that there is a God, but they do not believe that there is no God. For these people, it's worse to be committed to the wrong cause than to be committed to no cause. But, let's not mistake, they are committed -- to non-commitment. They will spend great amounts of time, effort, and emotion knocking down every possible argument for any particular religious position, and then insist they have open minds. I'm sorry, but I do not find anything particularly open-minded about the arbitrary rejection of anything smacking of the supernatural.
A certain segment of the unconvinced population style themselves "freethinkers". What follows are a few sections of a "non-tract" available from the "Freedom From Religion Foundation" (http://www.ffrf.org/nontracts/freethinker.php). I plan to produce a detailed response to the entire non-tract at some future date, but this document contains a few statements which typify some of the inconsistencies common to non-theistic thinking.
free-think-er n. A person who forms opinions about religion on the basis of reason, independently of tradition, authority, or established belief. Freethinkers include atheists, agnostics and rationalists.
No one can be a freethinker who demands conformity to a bible, creed, or messiah. To the freethinker, revelation and faith are invalid, and orthodoxy is no guarantee of truth.
It's probably just a careless error, but I find it amusing that in the second sentence, "rationalists" (those who base everything on common sense and reason) are treated as a group separate from atheists and agnostics, which would imply that atheism and agnosticism are not entirely rational. On the other hand, it also seems to imply that one could be a theist and still be a freethinker, but the rest of the non-tract makes it pretty clear that there is no such thing as a rationalistic theist (in the author's opinion).
The bubble moves a few more marks off level in the third sentence. "No one can be a freethinker who demands conformity..." pretty much sounds like a demand for conformity. "Revelation and faith are invalid", but we are to take the author at his word. "Orthodoxy is no guarantee of truth", yet in the following paragraph, the author defines how truth is determined, assuring us that if we remain faithful to these axioms, we will guarantee that what we believe is true.
Freethinkers are naturalistic. Truth is the degree to which a statement corresponds with reality. Reality is limited to that which is directly perceivable through our natural senses or indirectly ascertained through the proper use of reason.
Reason is a tool of critical thought that limits the truth of a statement according to the strict tests of the scientific method. For a statement to be considered true it must be testable (what evidence or repeatable experiments confirm it?), falsifiable (what, in theory, would disconfirm it, and have all attempts to disprove it failed?), parsimonious (is it the simplest explanation, requiring the fewest assumptions?), and logical (is it free of contradictions, non sequiturs, or irrelevant ad hominem character attacks?).
How many of these sentences, presented as absolutely true, meet the definition given in the last sentence, including the definition itself? How can anyone know the limits of reality without having logically transcended those limits? If your flashlight only illuminates to twenty feet, how can you say that no one is standing twenty-one feet away? Throughout the rest of the text the author makes many statements which are completely unsupportable and do not meet the given definitions of truth.
The concluding paragraph brings these inconsistencies full circle:
Freethought is reasonable. Freethought allows you to do your own thinking. A plurality of individuals thinking, free from restraints of orthodoxy, allows ideas to be tested, discarded or adopted.
Freethinkers see no pride in the blind maintenance of ancient superstitions or self-effacing prostration before divine tyrants known only through primitive "revelations." Freethought is respectable. Freethought is truly free.
The author spends the whole of his non-tract telling us exactly what freethinkers do and do not believe. More, he tells us in no uncertain terms what a freethinker can and cannot believe. He presents us, in effect, with the "Creed Of Those Who Reject Creeds". "Freethought allows you to do your own thinking", but only if you agree with other freethinkers that God (or gods) are "divine tyrants" or that the Bible is a "primitive revelation". "Freethinkers form opinions about religion without resort to authority", yet the author quotes prominent freethinkers and informs us of all of the social and scientific advances produced by freethinkers. "Freethinkers are not to form opinions based on 'established belief'", implying that every freethinker must figure out all of this completely from scratch, which pretty much defeats the purpose of producing the non-tract.
I do not want to downplay the role of reason here. But pure reason gets us only as far as the end of the "I Believe" section. All of the non-theist positions accept the existence of the material universe with which they have direct contact, but all three set arbitrary limits on what evidence they will accept beyond that and draw arbitrary conclusions about the concepts that are outside those limits. Atheists deny the existence of anything else, agnostics deny the relevance of anything else, and the unconvinced deny the validity of anything else.
Theists are those that have found convincing evidence in the material universe that points to the immaterial, "God" in the broadest sense. But, now I will switch to the narrowest definition of "God". Individual pieces of evidence may be controvertible, but they form a pattern that is only satisfactorily explained, to my mind, by the existence of the God of the Bible. Here is a very condensed list of the pieces of evidence that have led me to conclude, "I believe in God":
Looking through the list, it is obvious that I give great credence to the Bible as a historical document and as a vehicle of communication between God and humanity. Many polemicists make the Bible their point of attack. "How can we believe the Bible", they say, "when it contains so many inaccuracies and inconsistencies and was put together by a group of men with an obvious theological agenda?" At face value, I'd have to agree. I certainly wouldn't base my life around such a book. But, the hard evidence shows that these things are not true of the Bible, or are not really relevant. It is outside the scope of my purpose (and ability) to present a full defense of the Bible. I can say that a full defense is not only possible, but has already been made to my satisfaction. I've seen the lists of "Bible Contradictions", "Bible Absurdities", and the like, and have seen credible, well researched, reasoned responses to every one. Many of the theories of Bible formation are outdated (some are centuries old), and have not held up under recent scholarship and archaeological discovery. Many common assumptions and beliefs about the Bible have been shown to be untrue, based on an incomplete understanding of the people who wrote the Bible and the people to whom it was first given. I've read the polemics, the apologetics, the counter-apologetics, and the counter-counter-apologetics. The more I've read, the more I am convinced that the Bible is a solid basis for belief, and the only ancient document which can stand up to all attacks on that belief.
You may also note that the last reason in the list is a purely emotional one. Reading up to this point, you may have gotten the impression that this is all a cut-and-dried, measured-and-balanced, intellectual exercise for me, that my beliefs are the result of painting myself into a metaphysical corner. That is certainly not the complete truth. I come from good Scandinavian immigrant stock and I'm chock full of emotional reserve, but this is one area where my inner thoughts and feelings often break through. My faith is very much tied up in my very emotional reaction to what I find in the Bible, a reaction greatly lacking as I've studied other faiths. As much as my modern mind treasures reason and logic, I cannot discount the relevance of gut feelings. Emotions are a fact of existence. It may be unwise to be ruled by them, but it seems even less wise to consider them a barrier to truth. I find a great deal of comfort in the fact that my belief in God meets both my rational and emotional needs.