Natural selection is a nightmare for Evolutionists. This sentence might confuse many people. Aren't natural selection and Evolution synonymous? One might think that by the way modern Evolutionists argue. In fact, many of them often tell me explicitly that natural selection is Evolution. Meanwhile, it seems to take more effort than it should to convince them that the Bible does not teach the fixity of species. But the truth is, no. Natural selection is not Evolution, and in fact, Creationists were writing about it before Darwin. Hilariously, Darwin actually plagiarised a lot of his work from Creationists like Edward Blyth. But let's not talk about Darwin's questionable work ethics. Let's instead look at the full title of his book: "On the Origin of Species by means of Natural Selection, or the preservation of Favoured Races in the Struggle for Life."
Darwin never intended for natural selection to be Evolution. He proposed it as the mechanism by which Evolution occurs. However, the title of his book alone shows that he had at least some awareness that natural selection has only two functions: The preservation or the destruction of that which already exists. Long story short, natural selection is not a creative process, but a culling one.
We've all heard that natural selection can be best summed up as "survival of the fittest". If you're fit, you survive, you have babies, they share your fitness. If you're not fit, any offspring you have will also be unfit, and that's assuming you even have offspring in the first place. The "unfitness" is then removed from the gene pool.
Let us get a word in from Darwin, for a moment: "If it could be demonstrated that any complex organ existed which could not have been formed by successive, slight modifications, my theory would absolutely break down." (1) So, here we have a means to test Darwin's hypothesis. Darwin himself admitted that his theory would "absolutely break down" if it could be shown that a complex organ exists that could not have been formed by successive, slight modifications. Now here's the problem: every animal alive today has some kind of feature that provides a survival advantage now that it exists, but that would have hindered survival on its way to existence had it evolved by successive, slight modifications.
The heart is an excellent example, and personally it is the one I most like to use. The heart doesn't just provide a survival advantage, it is a necessity for survival. If your heart failed, or was destroyed or removed, you would die very quickly. But rewind Evolution a bit, is it still advantageous? No. See, hearts aren't just complex, they are irreducibly complex. There is no feature of the heart that can just be added gradually, bit by bit. Ask anyone with so much as a faulty valve, they will confirm that the heart is rather important.
And of course, the heart is not completely isolated. It's not like all you need is for the heart to exist and you're all tickety boo. No, the heart works in tandem with other organs. Where would the blood go if not for the extremely complex system of blood vessels? What would the heart pump if not blood? Where would the blood get oxygen if not the lungs? And how would the heart pump if not for the nervous system? So much needs to be in place for the heart to function that it simply could not have gradually evolved.
And it gets worse; there are other hearts in the world besides our own. Humans, after all, are not fish (despite what P Z Myers says). Neither are fish humans. Our hearts are different. Humans actually have what is called a double circulatory system. That is, blood flows through our hearts twice in one journey. It flows from the heart to the lungs, then back to the heart, then around the body, then back to the heart to start again. By contrast, fish have a single circulatory system. Their blood flows through their hearts only once in a journey.
So, here we're not just talking about the Evolution of a heart, but the transformation of one system into another. Do we imagine these mythical transitional forms would have a survival advantage over the originals? Far more likely that the result would be unfit, and swiftly go extinct. Thus, natural selection is a nightmare for Evolution because it presents us with the very thing Darwin said would make his story "absolutely break down." The heart alone is a complex organ that exists which could not have been formed by successive, slight modifications, and therefore, by Darwin's own criteria, Evolution has absolutely broken down, and by the very method by which it is supposed to work, no less!
Christianity has a comparable scenario. If it could be demonstrated that Jesus did not rise from the dead, Christianity would absolutely break down. From Genesis to Revelation, the resurrection is central. If the resurrection happened, you can trust the scriptures on everything. If it didn't, you can't trust the scriptures on anything.
Unlike Evolution, Christianity hasn't absolutely broken down by its own criteria. The resurrection happened. It cannot be demonstrated that it didn't, the best explanation for the historical evidence available to us is that it happened, and put simply, when you look at atheistic attempts to prove otherwise, it almost appears that they know it. We can be confident in our belief that the resurrection happened.
And this is great news! In Christianity, there is no "survival of the fittest", because the truth is, none of us are fit enough to survive God's judgements. Why? Because our hearts are faulty. (See what I did there?) But Jesus' wasn't. When He died on that cross, He did so without so much as a hint of sin. Jesus took the punishment we deserve for sin, and so we can receive the reward He deserves for His righteousness. All it takes is to confess Him as Lord and to believe that God raised Him from the dead. That just seems like the natural option to select.
References
1. Darwin, Charles - On the Origin Of Species, 1859