If I had to pick the one single thing that earns the most followers for theism, it is the explanation for why we are here. Theism provides the answers for why the universe, this planet, and life all exist in the first place. Kind of...
Philosophers and theologians have been struggling to figure out the "meaning of life" since the beginning of civilization with no definite answers. When I am challenged as to what I think the meaning of life is without a god, I always get a bit confused. Do theists really have that answer? Do they all have the same answer?
You see, theists may claim to have answers for why these things (universe, life) exist, but what are those answers? God did it? Sorry, but I'm still left to wonder why. In my opinion, we've gotten along just fine for a long time without the knowledge of the elusive "meaning of life" to guide us. Great minds have come and gone, pondering the question and making no conclusions. Is a meaning really necessary?
A classic theistic argument is the Argument from Design. Simply put, the universe and life are so complex and unlikely that they must have been set up, or designed, in order for things to be the way they are. If this universal constant were changed 5% then nothing would exist! or If the Earth were such and such distance closer to (or farther from) the sun, we wouldn't exist!
Fair enough. These things are absolutely true. To some, the mere fact that we exist is proof enough that there must be a god. Okay, fine by me. But there is an important point to be made, and I will refer to it from now on as the Lottery Argument.
I saw this somewhere else, but it really summed up my thoughts on the subject, so I am stealing it (with some modification). The Powerball is and inter-state lottery in the United States that about 10 (?) states participate in. The drawing of numbers is as follows (if this is incorrect, let me know): Five white balls are picked from a bin of 45, with the balls numbered from one to 45. A sixth ball, a red "powerball" is picked from a different bin of 45, also numbered from one to 45.
This combination makes the odds of winning exactly 1:54,979,155. One in almost 55 million. Statistics is not my specialty in mathematics, but I calculated the odds for getting your specific balls: 5/45 X 4/44 X 3/43 X 2/42 X 1/41 X 1/45 (the powerball).
Say I win this lottery. Someone usually does, eventually (after about 55 million tickets are sold). That would be great, and exciting. The jackpots range from 20 to 150 million dollars US. Half of that will go to taxes, but we're still looking at a nice chunk of cash.
Looking back, though, I'm troubled. The odds of me having the winning ticket were less likely than me being hit by lightning, or being bitten by a poisonous snake, or having a vending machine fall on me and kill me (no joke). The odds of me actually winning the lottery are so small that they are practically non-existent. In fact, most likely, the lottery was fixed so that I would win. That's the most reasonable explanation.
There's just one thing to remember: If this miraculous impossibility hadn't occurred, then I wouldn't be talking about how unlikely and, therefore, fixed it all was. If I hadn't won, I would have pointed out that the odds were poor, and it would be almost impossible for me to not lose a dollar on a worthless ticket.
If the universe weren't exactly the way it is, then we wouldn't be here to argue about whether or not it was designed. Exceedingly unlikely? Perhaps. I don't know. I've seen some numbers from Christians online who claim that the odds of life in the universe are far worse odds than those of Powerball, but I've never seen the actual calculation of these numbers. Doesn't matter. See Lottery Argument.
I am not a cosmologist, or a theoretical physicist, so I can't speak about big bangs or big crunches or quantum singularities with much authority. I am familiar with these things, but this branch of science is still very much in its infancy, and I would not categorize many of the theories as anything more than speculation.
To use the lottery analogy, it is entirely possible that millions of losing tickets have already been purchased. It is possible that millions of lifeless or short-lived universes have come into existence, and later crushed back in on themselves (as this one might eventually do).
It is also possible that other universes, with life, have existed. Is life really that rare? I would consider it presumptuous to claim that no other life exists here in this universe. Maybe this situation is not so suited for life. Maybe this universe and this planet are quite unfriendly to life. Maybe life has existed in spite of these things.
This brings up another important point about evolution and the universe. The universe and this planet were not designed for us; we were designed for them. Through slow, meticulous evolution, we have adapted to our environment. Through natural processes all species on this planet have changed specifically for this planet. Isn't this what we would expect? Perfect symbiosis with the Earth is not because of the Earth--it doesn't bend over backwards for the likes of us. We have bent, and are bending, over backwards for it.
I have also seen the claim made that DNA, the "blueprint" for life, is clearly designed. It is likened to a language, which is not too far off. DNA consists of four molecules, or the "letters" of the language. (Ironically, the different molecules are written as T, A, N, C, for short.) These "letters" form twenty different "words", amino acids, which make up all the proteins in our bodies.
The idea that these specific combinations, out of the huge number of possibilities, exist at all indicates divine influence to some people. These amino acids, and their proteins, have very specific purposes and can be applied to nothing else. The order of the body, and the fact that the exact instructions exist exactly where they are needed cannot be by accident, it is said.
Remember the Lottery? Maybe someone could explain to me what type of creature would have the wrong proteins, or a fundamentally flawed genetic code? What would this thing look like? How would it live? I'll even go so far as to say that such creatures have lived in the past, and probably even within the human species. The key is, they either (1) don't live long enough to mate, or (2) are deformed and different, decreasing the likelihood of mating. Either way, such errors don't last long in the gene pool.
There is a style of argument, sometimes called the Argument from Ignorance, that I hear a lot. In simple terms, it says: Well, I can't imagine how it could be otherwise, so I'm right! I would just like to make a distinction here, because my arguments so far might sound like that. I am not saying that I can't imagine it otherwise. I am saying that by the definition and nature of things, it cannot be otherwise. I can assure you that fundamental contradictions are separate things altogether from my own ignorance.
All these things, like the origins of the universe or the meaning of life, are really nothing more than fanciful mental exercises. People throw out some wild theories, they do some "soul" searching, and they come right back to square one. Will there ever be answers for these things? Maybe about the universe. When it comes to the meaning of life, many people agree that the pursuit of the answer is the real meaning. Can we say "circular logic"?
As usual, I am left unconvinced. There's one thing I can say, though. Despite the bold claims, theistic religions really don't offer any answers to questions about the universe and the meaning of life. If the universe were different, humans wouldn't exist exactly as they are today. Instead, life would probably still exist, but different--adapted to the different environment. It seems that science (evolution), provides better answers to these questions than faith. I can't imagine how it could be otherwise!