Aside from the claims of the problem of evil in the world (which I indeed ace in arguments), probably the number 2 stumbling block to the faith, bar none, has to be the problem of the often far-fetched beliefs we Christians have. "Really? The dead can come to life?" they often ask. And they do indeed have some good points... but let's face it? Who's asking the question? People who often believe things that, if true, would be hundreds, thousands, even millions of times more miraculous than things like the resurrection of Jesus and/or Exodus, bar none.
Take Darwinism, for example. Christianity and Darwinism do indeed have a lot in common, do they not? Both cases involve belief that somehow, in one way or another, dead matter ― that is, mere chemicals ― can somehow come together to become complex and eventually come to life. Likewise, the order (but NOT the duration) of Darwinian events ― the Big Bang (Genesis 1:3), the formation of the skies and oceans (Genesis 1:6), the formation of continents (Genesis 1:9), the formation of plant life to remove CO2 from the atmosphere (Genesis 1:11), the rise of sea life in the form of the Cambrian Explosion (Genesis 1:20a), the rise of proto-birds and dinosaurs (Genesis 1:20b), the rise of mammals (Genesis 1:24), and, finally, the rise of mankind (Genesis 1:26) ― is indeed echoed to a good 99.9% accuracy in the Bible. Really, the only, I repeat ONLY, difference between Christianity and Darwinism is that we Christians believe in a catalyst FOR these events, and that's God. Darwinists don't.
Right there, we hit a snag: Belief that dead matter (and, by extension, the dead) can come to life on its own, without a catalyst, without a creator, is belief in something millions of times more miraculous than belief that there is a God who CAN make that happen, and who CAN make the conditions favorable for it to happen. We Christians know that blind Darwinism ― without any catalyst (like a God) to somehow keep it in check ― is statistically, logically, and mathematically impossible. The odds of all that dead matter ― all those mere chemicals ― becoming life, if there is no God, are odds that are not only mind-boggling but computer-boggling, supercomputer-boggling, data-center-boggling, GPGPU-boggling, and boggling to just about any intelligence ― natural and artificial ― that we human beings can possibly conjure up. Odds that only make sense at all ― really ― if there's a God to manipulate those odds and spin them to our benefit. Without a God, there's obviously a near-perfect chance Earth would still have that same dead matter today as it did billions of years ago.
Yeah, it is indeed a miracle that this Earth is in such a perfect Goldilocks environment for life to form, there's no doubt... Scientists have indeed been looking for other Earth-like planets, and they've indeed found ones thought to have Earth-like Goldilocks orbits around other stars... ah, only to find them to move out of their Goldilocks orbits and either toward or away from their suns in elliptical fashions. Which, right there, puts Earth in a category of its own: Earth's orbit, compared to these others, is so close to being circular, there's almost no contest... Whether at aphelion or at perihelion, Earth is still within that perfect habitable zone, which it has to be for life to form. This, of course, just made the odds of finding extrasolar life that much slimmer, because all the exoplanets they've ever found that orbit in Goldilocks zones have orbits far more elliptical than Earth's, making the temperatures fluctuate too dangerously to be stable enough for life to form. Without a God, there's a good chance Earth's orbit would be just as elliptical ― and, thus, too climatically unstable for life to exist ― as theirs.
The proton-proton chain odds prove a similarly perfect-balance type scenario: The Sun's matter-to-energy conversion rate (thanks to the proton-proton chain) is at a perfect 0.7%, and with good reason: Decrease that figure by a tenth of a percent, to 0.6%, and plug it into computer models, and you get a grim picture: even if the atoms fused at first, the energy needed to sustain the reaction wouldn't exist, and thus, the fusion reaction would be very short-lived and, thus, unable to sustain itself. On the contrary, increase it to 0.8%, and the fusion reaction gives off enough of the matter as energy to render stellar and/or supernova nucleosynthesis impossible, and, by extension, render hydrogen the only matter that could exist in such a scenario. Without a God, this degree of perfection needed to make the universe fit for our existence ― let alone survival ― would indeed be statistically impossible.
All across the board, scientists are finding these statistically impossible scenarios, yet they continue to ignore them. It's as if they're saying "Oh, I know the odds of us not existing without a God are nearly 100%, but I don't believe in God anyway". Ah, and that's precisely why I can be a geek and yet a believer at the same time: because as a Christian, I actually have a logical, philosophical explanation for these odds, and of one who's able to spin those odds to our benefit. If only the world would just see that...