A Logical Proof
Recently I've been reading up on the Baha'i faith. I've been somewhat disappointed by the faith presented so far. While they do seem to hold reason and even scientific inquiry as points of doctrine, their doctrine has, in other areas, not managed to escape the irrational failures of more-established monotheistic religions. I did a little research into the authors of the linked book, and discovered that one of them formulated a tidy little proof of the existence of God.
In summary, it goes like this:
1) Everything in the universe is either preceded by a cause or else contains within itself a sufficient reason for its existence.
2) For every system or composite phenomenon, any cause for the system is also a cause for every part of the system. (Every material thing, except possibly the elementary particles of quantum physics, is composite.)
3) The existence of a whole system cannot precede the existence of its components (or, he writes, "the constitution of a whole obviously supposes and depends upon the prior or simultaneous existence of its components."
For a more complete version, see here. I'll note that both of the last two links lead to what appears to be an official Baha'i site, which I'll be looking into in more depth when it isn't two thirty in the morning.
Considering the summary, my major complaint is that following the axioms* to the conclusion "God exists" is a non sequitur. All these principles have demonstrated is that a complex entity cannot be self-caused. Trying to apply this to the existence of the universe (ie, therefore God) isn't really a valid use of this conclusion. The Big Bang model doesn't require, as far as I know, a self-caused universe in the absence of God. The universe expanded from a singularity, it was not self-causing. We might then ask what caused the singularity, but here we run into one of the fundamental disagreements between science and religion. Science is content to explore the answer, whereas religion is content to declare "therefore, God." At least until the data comes in.
Religion is a virus.
Fight the infection.