Well, why not?
I strongly disagree with the assertion that Christians rely on blind faith -- a mentality of "do not question, because it just is the way it is." Obviously faith is the very core of Christianity. But that doesn't mean that faith has to be blind.
Quite to the contrary. There are a lot of different ways to find concrete evidence behind the age-old question, "Is there a God?" There may not be a smoking gun that can positively, definitely prove the existence of a divine presence for non-believers, but certainly there's enough circumstantial evidence for probable cause. For starters, there are the very questions that science have thus far been unable to provide an answer for regarding the origin of life. Darwin's theory of common descent can explain physical life. Lemaître's Big Bang Theory can explain the universe that's inhabited by that life. But how do you explain the existence of the particles that would eventually create the "big bang"? It's easy to say, "Well just because science can't prove how it started doesn't mean God is real." Of course not. But if you trace the origins of this whole grand scheme we call existence far enough back, you will eventually arrive at a point where
something had to come from
nothing. And something doesn't come from nothing unless someone or something created it. I can't really wrap my mind around the idea of the omnipresence of God -- that he just always was. But neither can I wrap my mind around the idea of something coming from nothing. And if something came from nothing, why not a divine presence? And if it was a divine presence, why not the God my faith is placed in? Sure, there are a lot of different gods that are worshiped by people of different faiths. But let's not forget that most of the world's foremost religions -- Christianity, Judaism and Islam -- all worship the same god, even if they fundamentally differ on just about everything else.
But that isn't the real point of my post. Nor is the scientific and physical evidence that points to the existence of a divine god. Instead, it's the simplicity of the historical record. I say simple, because it really is: We know, from the secular historical record as well as the religious historical record, that a man named Jesus lived ~2,000 years ago and claimed to be God in the flesh. No secular historian who is considered relevant has ever offered evidence to dispute this. The actual existence of Jesus cannot be ignored. If Jesus was who he claimed to be, God is real. If he wasn't, God isn't.
We know, from secular and religious historical texts, that Jesus developed quite a following but that he also generated a lot of hatred, particularly among followers of Judaism, and we know he was eventually executed. Even if the death of Jesus was the end of him, he was one of the greatest and most influential teachers mankind has ever known. But if the death was the end of him, it would shatter the very tenements of Christianity. What, then, became of Jesus's body? After all, the only point where secular history and religious history dissent is what became of Jesus after his death. The facts of his life, his ministry claiming to be the son of God, his arrest and his execution, none of those things are disputed.
So what became of his body? Was it, as Rome's top brass claimed, removed from the tomb and hidden by his followers in a move to fulfill his predictions and protect his legacy? That would be the easiest way to explain it all away, but what about those who knew Jesus personally who went to their grave proclaiming him as God? That's where things get particularly interesting. Many of the disciples who were Jesus's closest followers and confidants were executed because they refused to renounce him, and several of them died very cruel deaths. None of them renounced him. Those simple acts of defiance to the Roman Empire speak volumes. As has been written, most of us would have little problem living for a lie, but how many of us would be willing to die for a lie? These were the men who were there when Jesus died, and they were the ones who claimed that he came back to life three days later, who claimed to have seen him after his resurrection and who claimed to have seen him ascend into the sky. If it was all a lie, if they had to steal Jesus's body from the tomb and hide it in order to protect Jesus's legacy, would they really have been willing to die, often cruelly, to protect that lie? I don't know about you all, but I have several friends I think I would be willing to give my life for. (I say "think," because it's easy to talk a big game until you're actually staring adversity in the face.) But I don't have any dead friends I would be willing to give my life for. And I guarantee you I wouldn't give my life to protect something I knew to be a lie about one of my friends, whether they're dead or alive. If those men had seen that Jesus didn't arise from the dead, as he had promised them he would, would they really have faced torturers and executers without crumbling? Not even one of them? Their deaths are different from the many other early Christians who were martyred over the years (and, actually, are still being executed for their faith even today). Those Christians were and are being killed because they refuse to renounce their faith. And that's admirable, but different, because they never saw the man named Jesus in the flesh. The early disciples saw him. They walked with him. They knew his most closely-held secrets. And they died, some by the sword, some by crucifixion, and some naturally, ALL claiming that Jesus's execution wasn't the end of him. That's remarkable and, in my opinion, the greatest physical proof of God's existence.
Don't get me wrong; I don't need all that to prop up my faith. Like everyone else who claims to be a "born-again child of God," I can say without hesitation that God revealed himself to me years ago. As a Calvanist Christian, I firmly believe that God finds us, not the other way around. And once that happens, he manifests himself in us. It's an emotional, spiritual experience that most people will never understand and that a growing number choose to mock or belittle, and that's okay. Religious beliefs are a very personal thing and I'm okay with others not sharing my beliefs.
But for non-believers who are questioning the existence of God, I think all of the above is relevant. If you can study the writings of Pontius Pilate to Caesar Tiberius, and all the other secular accounts of Jesus's life, and come away 100% convinced that God is just some fairy tale, some "sky daddy," that's your right. I don't think I could. But that's just me.