[This was originally a forum post on ThoughtCommunity.com, replying to a post in which the Ontological, Cosmological, and Teleological arguments for God's existence were brought up as conversation starters]
Whew. Well ain't that a can of worms!
If you'll permit me to misconstrue the ancient and traditional meanings of the words, I would draw corollaries between the arguments you mentioned and what I see as more-or-less modern manifestations:
From the Ontological argument I would draw a connection to the argument from personal experience and/or the Anthropological argument. Like much of medieval/renaissance philosophy, it's hard to make the Ontological argument look credible in light of modern perspective. Making the jump from cause->effect to imagination->reality (Rather than reality->imagination, which leaves reality as only a subset of imagination) not only seems absurd and backwards in our (albeit lacking) understanding of the brain (As a computer science major I have to disagree with Locke, among others, who claimed the brain could not naturally give rise to thought without supernatural interference), but is can far too easily be abused satirically (Anything deep that I can conceive of is reality?).
Many Christians, however, defend their faith on the basis of personal experience -- evidence they've seen in their own lives of supernatural involvement. Sometimes this is emotional (Feeling the spirit) or more miracle-oriented (Basket of fruit on the front door during financial crisis). It's often held that one must have such experiences for him/herself, and that God works individually to convict each individual via their own unique path. As such it can also be used as a defense against the argument that science has not discovered global proof of God -- "God doesn't operate that way," one might say.
The Cosmological argument is, of course, very popular. It is often iterated from the pulpit as a direct challenge to the big bang paradigm to show its incompleteness. "I say in the beginning God, they say in the beginning rock" says Kent Hovind in his rhetorical style. To me this just feels like a God of the Gaps technique, as if to say "we don't know, ergo God."
The Teleological argument is familiar today. From talk of the fine-tuned universe to ID and Creationism, this is where the loudest of proponents of religion who purport to stand on science find their base. The former is related to the Anthropic Principle, and while I find the details and nature of the universe to be stunningly amazing and mysterious, I personally hesitate to make any sort of supernatural conclusions about the nature of something about which we know so little.
Intelligent Design and especially young-earth Creationism (YEC) feel absurd to one infused by the perspective maintained by academia -- much like white supremacy seems absurd to most raised up in the modern west, where our schools work so hard to establish a perspective of equality of individuals regardless of their race (Largely as a reaction to the 20th century push for eugenics) -- and much like the marriage of gays in California is seen as an abomination by conservative Anglicans in Uganda, or Muslims in Iran.
As such, non-naturalistic depiction of the origin of life must begin in the west as an caricaturization of academia as too pro-naturalistic. ID and YEC both purport to be beacons of light pointing out evidence and truth that has been overlooked by the bias that pervades the scientific establishment. They cite how difficult it is to get published in academic journals, and how evolution is taught as well-established fact in schools. Some claim that this is the result of a desire that God should not exist, with the aim of being liberated from the divinely prescribed lifestyle -- thus blaming the dominance of evolutionary theory not on science but hedonism and amorality. No wonder YEC is widely considered a conspiracy theory (Of course, evangelists, like the aforementioned Hovind, who lack critical thinking probably help most to establish that image).
I'm not saying that it's impossible -- cultures are like people, and they hold certain assumptions and biases along with the same unwillingness to change -- but I'm extremely skeptical of an idea that must not only establish itself empirically but also tear down all of the worlds empiricists in order to even appear valid. The "bias" within the YEC movement seems much stronger than that without, arising almost exclusively from a desire to affirm an already-held literal belief in Genesis, and while some Creationist/ID individuals and institutions do publish good science (And we always need someone who is willing to challenge the status quo with rigorous critical thinking), overall I find it very difficult to see merit in the paradigm. Most importantly, it is not conclusive in any way -- the arguments are not strong enough to give one enough confidence to leave agnosticism.
I don't pretend to be able to give a "conclusive" argument for naturalism either. Given the paradigm that I am immersed in, it all seems to make sense: microwave cosmic background radiation establishes the big bang and the age of the universe, mathematical theories explaining the origins of stars and planets have existed for hundreds of years, the evolutionary explanation of life is grandiose, but by all outward appearance (I'm not a biology student) the fossil record, age of the earth, and macroscopic similarities between animals seem to support it, and the usefulness of natural selection in evolutionary computing (The field I want to go into) is an added plus to its cogence and apparent viability.
What "seems to make sense" to any individual, however, is primarily cultural. It's based on what I read in canonical books, it's based on what I sense in society around me, and it's especially based in how many friends I have to resonate with -- and thus gain confidence with -- on the issues. Some of you have heard me recently talk about "indulging in youthful arrogance" when talking with you, because while I enjoy the sensation of being agreed with (And thus making my world less gray and insecure), I at least try to be aware of the fact that much of those feelings are purely social and emotional more than they are rational.
I can have a strong feeling that something is true without being able to give a thorough, rigorous argument for it. This is good, I suppose, or we wouldn't be able to believe much of anything . A recent example: As of about two days ago, I feel like I understand how Einstein's General Theory of Relativity follows from the Special Theory, which I've understood for quite some time. The Special Theory is hard enough to explain, and when I was fifteen I went through quite the mind-rending process to be able to comprehend time dilation -- but the General Theory is even more difficult. How the blazes does the constant speed of light imply curved space? Seems like apples and oranges. Now I understand... I think... but there is no way whatsoever that I could explain it to you, not without much more study. Unfortunately, that also means that as of yet I do not know if this undeveloped path of reasoning, this belief of mine, is right or not: A flawed conjecture would feel just as true until it underwent the rigorous process of discrete communication.
Now, delving back a ways into my own journey, you can find some treatment of Bible Prophecy in a paper I wrote a year ago (Here). By the time I was writing it I had grown primarily skeptical, but to this day I feel that the 70 week prophecy of Daniel 9 (See an earlier article here) is one of the best arguments for the existence of a supernatural being -- and furthermore a personally involved supernatural being -- that I've ever been exposed to. Again, however, one is forced to take a few shortcuts in reasoning, and assume that certain interpretations (Best-guesses) are valid even though there are many more to choose from, and so it is not conclusive in any way. Such uncertainty is inherent, however, not only to history and archaeology but to all of scientific exploration, and so non-provability does not immediately imply that the idea is non-valuable.
As for me personally, I currently call myself a secular humanist, naturalist, and -- just for fun and dreaming's sake -- a transhumanist. I do, however, take great pains to seek self-understanding, to juggle the biases inherent to any point of view, and to respect the fact that the world is gray, and while certainly some ideas are more true than others, individuals cannot be blamed for failing to separate the wheat from the chaff, since I'm guilty of the same short-sightedness.
SigmaX