Hello Dr. Sing,
I'm very familiar with all four arguments, so I'll just briefly summarize my disagreements with all four.
1. The Ontological Argument
To say that God must exist because he is the ultimate perfection assumes that something exists which has the ultimate perfection. Furthermore, one can think of a lot of things that are perfect, yet which do not exist. I could think of a "perfect" island, or a "perfect" rabbit, but that doesn't mean that either exists.
2. The Cosmological Argument
The cosmological argument basically tells us that every observed effect has some kind of cause. Let's just assume this to be true, although I'm not sure that it need always be the case. Causes always precede their effects. However, if time began with the Big Bang, there would have been no "before" where a cause could have taken place.
Creation takes time. There has to be a moment when the creation does not exist, followed by a moment in which it does, otherwise it wouldn't make sense to say there was a moment of creation. Now if T=0 was the Big Bang there would be no "before" the beginning, at least not in a meaningful sense. If so, what does it mean to say that the universe was created? Subsequently, how does one fit a creator into such a scenario?
3. Teleological "Fine-Tuning" Argument
This was once my favourite argument for God's existence. However, after giving it some serious thought, it almost seems the worst argument. Yes, the universe does have certain traits that allow us to exist. It also has a lot of qualities that are very detrimental to human life. As far as we know, Earth is the only planet with any kind of life. Not particularly impressive if the universe was carefully "fine-tuned" for life. Even our own planet would not have been comfortable for human life during much of its history. Not to mention the massive extinction events that have taken place in the past, wiping out most of the planet's biodiversity.
It is impressive, looking at the rest of the barren universe and marveling at how well suited our planet is for life. It is impressive that we exist at all given how hostile the universe is. But a universe barely capable of sustaining any life is not good evidence of careful fine-tuning, unless the Creator was satisfied with a sloppy job.
4. The Moral Argument
Dr. Sing writes:
We all know that animals lack conscience. They steal, but do not feel guilty. They kill, but do no view it as a sin.
This would be interesting, were it true. But other animals have been observed acting morally. I'm too tired and lazy right now to look up specific examples, but check out the wiki article
Altruism in Animals
Most of the behaviour can be chalked up to simple instinctual behaviour (although human morality is probably instinctual to some extent). But more intelligent social animals, like chimpanzees, have morality that closely resembles our own. They behave altruistically, sharing food with each-other. Dolphins have been observed lifting wounded conspecifics to the surface, and even, I believe, doing the same for human swimmers.
We humans have much more complex social behavior than dolphins and chimps, and this is why we're able to live and function in larger societies. It is not surprising therefore that our parents teach us to behave in such a manner that we can function within the societies we are born.
Respectfully,
-A tired Meldinoor *yawn*