You're a skeptic - Good!

Are you a non-believing skeptic, I am glad that you are willing to examine the evidence for the existence of God and to explore whether Christianity represents truth. I think that skepticism is good, even for a Christian, since there are many "Christian" ideas floating around that are either false or non-biblical. An excellent article on Christian skepticism can be found at John Cassidy's site.

As a skeptic, I hope you are willing to examine the evidence without being committed to any preconceived ideas. If you consider yourself an agnostic (one who doesn't claim to know whether God exists or not) I think you will probably be much more willing to look at the evidence with an unbiased attitude. Atheism, on the other hand, is a belief that God does not exist - something that cannot be proven, unless one were God.

In reality, the existence of God cannot be proven or disproved absolutely. In fact, I cannot prove that you exist. Since God's existence cannot be proven, how do we determine if God's existence is probable? I propose using the same standard that we use in science - the 95% confidence interval. If you set no standard for evidence, the tendency is to raise the standard for proof as the amount of evidence increases. The standard I propose is a 95% certainty that God exists (and a 5% certainty that He doesn't exist). There are many things that we do everyday for which we do not have absolute certainty of the outcome (see 100% Convinced vs. 100% Committed).

We travel to work without being certain that we won't be killed in an accident. Even without absolute certainty, we believe that we will be successful. This is the kind of faith that I am advocating.
Sort out what is testable

Not everything in the Bible is testable. The miracles of Jesus were reported by eyewitnesses, but the witnesses themselves are now dead. Non-believing witnesses also reported these miracles. Jews who did not believe Jesus was Messiah stated that they believed that His miracles were done by the powers of the devil (note that they did not deny that the miracles occurred).1 Therefore, I propose eliminating miracles from the body of evidence. Even if they seem unlikely (which is the definition of a miracle) this fact cannot be used to discredit belief. God, by definition is supernatural, so it would not be surprising that He is capable of performing supernatural miracles.

Use the scientific method and the standard scientific criteria for proof
Therefore, one should examine how a religious work (such as the Bible in the case of Christianity) describes the creation and determine whether this description is accurate (using the proposed 95% level mentioned above). Yes, you are going to find statements that don't make sense or seem inaccurate. In the case of the Bible, some of this is due to translation difficulties (I have seen a few dozen of these). People who are committed to atheism look for translations of certain passages that seem to contradict known facts. One should look at alternative translations (and the context) to determine what the passage is actually saying (and who is actually saying it - some statements are meant to be false). Ultimately, if you find that 95% of the testable information in the Bible is true, you should become a believer.
"Proof" that God cannot exist?

Those are some my general observations and recommendations for examining the evidence for God's existence. I have seen several web sites produced by atheists who claim that they can prove that God does not exist. However, all of these atheistic arguments against the existence of God use some form of straw man argument, because they argue against the existence of a god who is significantly less powerful than the God described in the Bible. The Bible says that God is transcendent (exists beyond the three physical dimensions of the universe)2 and exists beyond our dimension of time (the Bible states that God was acting before time was created).3 Atheists argue against the existence of a god who is finite and limited to a single dimension of time. This is the straw god who cannot logically exist. In fact, there are religions that are logically impossible.

For example, the god of Mormonism is a former man who became a god. He had a father, who had a father, etc. One runs into the problem of where the first God came from. In contrast, the God of the Bible had no father, but is eternal, existing in at least two dimensions of time.

Atheists often use arguments that are logically flawed. For example, I very often hear the argument that if the universe were not finely tuned, then we would not be here to discuss it. In other words, since we are here, the universe must be finely tuned to support advanced life. The argument commits the logical fallacy of converse accident, applying an exception to a generalization when the generalization should apply. There is no logical reason why our being here would cause the universe to be finely tuned and we have no evidence that more than one universe exists. The generalization must apply when we have only one example.
According to naturalism, the universe has no purpose and no interest whether or not there is life in it. Logically, we should not be here. In fact, modification of laws of physics almost always results in universes that don't even contain matter! Our presence in the universe suggests that we are not here by accident. In fact, the atheist must address the question of why there is anything at all. Why should there be a universe instead of nothing?

Characteristics of the Christian God
Biblical arguments for God's existence appeal to a God who exists beyond time and space. Any other kind of god is logically impossible. There is evidence from the creation that the Creator (or creator, if you believe in naturalism alone) has these characteristics. When you solve the equations of relativity for time, you find that time began at the moment of creation (i.e., Big Bang).4 Whatever, or Whoever put in motion the events that formed the universe must have operated in another dimension of time. Atheists try to get around the problem that time began at the Big Bang by appealing to a breakdown of the laws of physics before 10-43 seconds after the initiation of the Big Bang. However, we will never have any scientific evidence that these "different laws" ever actually existed.
There is also evidence for the existence of extra dimensions of space (although they obviously must be located within our universe or else we could not detect them). The unification theory states that the four forces of the universe can be unified into a single force at the moment of creation. However, for this theory to work mathematically requires the existence of at least 9 dimensions of space and time.5 It has been shown that at least two of the fundamental forces of physics can be unified experimentally. Evidence for the unification of some of the other forces is likely within the next ten years. Nearly all astronomers accept the hypothesis that the universe arose from extra dimensions of space and time. The Bible claims that God exists outside of the universe, which requires extra dimensions that exist even outside of the six extra dimensions thought to be required for the existence of the universe.

Origin of the universe - design or chance?
Once you arrive at this conclusion, there are two major mechanisms, neither of which are testable experimentally. The first is a naturalistic interpretation, which states that the universe arose from some super universe by an "evolutionary" process. The universe is so finely tuned that this is the only reasonable explanation for how our universe happens to be suitable for the formation of stars, planets, and life. The formation of a single universe with exactly the right combinations of laws of physics, size, etc. is so unlikely by chance as to be impossible. The person who believes in naturalism alone must also believe that a super universe exists which is capable of producing an almost infinite number of other universes with vastly differing laws of physics. They hypothesize that our universe just happens, by chance, to have the proper set of laws to allow for the formation of stars, planets, and life.

The Big Bang - a BIG problem
The Big Bang presents a big problem for the atheist (at least for those who have really thought about it). The Big Bang began about 14 billion years ago and will most likely continue to expand indefinitely, according to the latest scientific evidence. Even if it is found later that the universe contains enough matter to cause an eventual collapse of the universe, such a universe would end as the "Big Crunch" rather than expand to form another universe. For atheism to work, the universe must be eternal. Here is Andrei Linde's admission:

The first, and main, problem is the very existence of the big bang. One may wonder, What came before? If space-time did not exist then, how could everything appear from nothing? What arose first: the universe or the laws determining its evolution? Explaining this initial singularity-where and when it all began-still remains the most intractable problem of modern cosmology.
Atheists' problem - Fine tuning of the universe

For example, recent supernova evidence has shown that the universe probably possesses a cosmological constant - a universal "repelling" force that accelerates the stretching of space as objects become further apart from each other. In order for the universe to contain stars and planets, this constant must be fine tuned to a level of a part in 10120. Such an extreme level of design is almost incomprehensible. In my discussion with atheists, several have told me that they are comfortable with the idea that such levels of fine-tuning could have occurred by chance in our single universe. Such a proposal is completely illogical, and, in fact, requires more blind faith than to believe that God designed the universe. In fact, in order to be a logic-based atheist (as opposed to a faith-based one), you must believe in the multi-universe theory. Not only that, but you must believe that there are more universes in existence than the number of all the subatomic particles that exist in our universe. Don't believe me? Here is what a recent article from Science says about this hypothetical "multiverse" spinning off an "infinity" of other universes:

Uncomfortable with the idea that physical parameters like lambda [cosmological constant] are simply lucky accidents, some cosmologists, including Hawking, have suggested that there have been an infinity of big bangs going off in a larger "multiverse," each with different values for these parameters. Only those values that are compatible with life could be observed by beings such as ourselves.
Luck has no place in science, since all events must be probable (on the basis of all possible events) in order to actually occur.

Atheists' solution - untestable "science"
What scientific evidence exists to support the multiverse model? None! Not only is there no evidence, the physics of our own universe requires that we will never be able to obtain evidence about any other universe (even if it does exist). Therefore this belief is, and always will be, based solely upon blind faith (sounds like a new religion to me)! Why are some cosmologists "uncomfortable" with the idea that the cosmological constant (lambda) is so finely tuned? Simply because such fine tuning suggests design and (oh no!) a Designer. A hypothetical, untestable, complicated model of a super universe is the only alternative to belief in God. Such belief is not based upon science, since science requires that hypotheses be testable, but is based solely on the "hope" (i.e., belief) that there is no personal God to Whom we will be personally accountable.

Even evolutionists now admit that such ideas amount to nothing more than metaphysics. In a recent discussion of the origin of life, the The Origin-of-Life Foundation, Inc.® made the following admission:
"Appeals to multiple or "parallel" cosmoses or to an infinite number of cosmic "Big Bang/Crunch" oscillations as essential elements of proposed mechanisms are not acceptable in submissions due to a lack of empirical correlation and testability. Such beliefs are without hard physical evidence and must therefore be considered unfalsifiable, currently outside the methodology of scientific investigation to confirm or disprove, and therefore more mathematically theoretical and metaphysical than scientific in nature. Recent cosmological evidence also suggests insufficient mass for gravity to reverse continuing cosmic expansion. The best cosmological evidence thus far suggests the cosmos is finite rather than infinite in age."

According to Paul Davies:

"Whether it is God, or man, who tosses the dice, turns out to depend on whether multiple universes really exist or not….If instead, the other universes are…ghost worlds, we must regard our existence as a miracle of such improbability that it is scarcely credible."

Theistic solution - measurable design
On the other hand, the deist says that God designed the universe with just the right laws of physics. Note that neither hypothesis is testable, but that the God hypothesis is much simpler. The naturalistic explanation requires the presence of a complicated, unproved super universe that has the capacity to randomly spew out an infinite number of universes with different laws of physics. How does this hypothetical super universe know how to do this? Why would it even want to do this? Ultimately, why should there be any universe at all? None of these questions are logically explained by naturalism. Only an intelligent Being would be motivated and expected to produce any kind of universe such as what we see. If we use Occam's razor, which states that one should use the simplest logical explanation for any phenomenon, we would eliminate the super universe/multi-universe explanation in favor of the simpler God-designed universe model. The evidence for design in the universe and biology is so strong that Antony Flew, a long-time proponent of atheism, renounced his atheism in 2004 and now believes that the existence of a Creator is required to explain the universe.

Check this site for more info:
http://www.godandscience.org/apologetics/atheismintro.html