Because God is not available for us to touch and see, physically, and because there is no knock-down argument for the existence of God, then by definition people are going to disagree about God. Again, that’s simply the way it is.Honestly, when people say things like that, I hardly know where to start for the sheer number of things I want to say. Granted that Jesus of Nazareth is not physically among us today, so in that sense "God is not available for us to touch and see" today as he was in Peter and John's day, and in Thomas the Skeptic's day. Yet are we really willing to approach a discussion about God as if Christ had never walked among us, as if no one had ever touched and seen him, as if never in the history of the world had God done anything that made it plain that he is there?
Many Christians seem to think that they must first convince someone that God exists and then convince them that Jesus is historical and then convince them that the New Testament is reliable (or even inerrant), and only then do they think it is fitting to discuss Jesus. I think that is an incredibly unproductive approach on practical grounds, and that it is also on shaky theological grounds. Why? If God raised Christ from the dead, then God exists. Just as the human argument for our own existence may be "I think, therefore I am", so the argument for God's existence from the resurrection: "He acts, therefore he exists." The same would apply to any miracle on which we were willing to take a stand for its reality: If Moses led Israel to freedom accompanied by God in a pillar of cloud and fire, then there is a God. If Jesus raised Jairus' daughter from the dead by the power of God, then there is a God. If Jesus raised Lazarus from the dead by the power of God, then there is a God. If Jesus raised a widow's son in the town of Nain by the power of God, then there is a God. For each of those, there are reasons why or why not to take a stand there in particular. But the best-attested act of God in the history of the world is the resurrection of Christ, also being the means by which God reaches into the world. Here every Christian should be willing to stand on the reality of God's action. If Jesus rose from the dead by the power of God, then there is a God.
Here is some food for thought. I read an encyclopedia article once that had information on various religions. When it came to Christ, there was mention of the usual biographical facts: maybe some mention of his connections with Nazareth and Capernaum, some basic teachings, his final trip to Jerusalem, his death there by crucifixion. And, it continued, "his followers believe he rose from the dead." It hadn't qualified anything else it had said. It hadn't said "his followers believe he was condemned by Pontius Pilate"; after all, every source we have on the subject agrees on that. It hadn't hedged that "his followers believe he taught about the coming of the kingdom of God"; every source we have on the subject agrees on that. Well, you know, every source we have on the subject also says Jesus' tomb was empty the third day out. We have more early letters and memoirs and such writings on the subject of Christ's resurrection than we have on the Pontius Pilate bit. And nevermind getting an atheist to think the Bible is inerrant; it is enough to believe the authors of the gospels were basically honest and sane, because nobody who is honest and sane is wrong on that level for that length of time about that many things. Either the authors of the gospels had some serious issues, or they were at least in the ballpark. And if they were at least in the ballpark, then we have the records of the most remarkable thing ever to happen on this green earth. And yes, it means that God acts, therefore God exists. It also means that God redeems, therefore God is good. (I mean, consider Luke: consider how carefully he checked into what was the title of this official or the details on the place; he has been shown to have been careful and diligent if not inerrant. People fault him for minor things but acknowledge he was by and large careful. Well, are we supposed to imagine that someone who is by and large careful still manages to be 100% wrong about everything that matters on dozens of different incidents that were his whole purpose for writing? Come on.)
I think the part that bothers me there is when Christians will not take their stand on Jesus' life, death, and resurrection, but instead run to other ground to take their stand elsewhere, as if it were more foundational or more certain or more important; often it is only more easily dismissed. I'm not arguing against doing apologetics, by the way; I've done and still do apologetics. What I am saying is that there is a difference between apologetics, which is defensive, and evangelism, which is forward-moving, and that many people do not know when to use the one versus the other, or even -- honestly -- how to evangelize. Many evangelists are frustrated at a lack of results without really understanding the tools in their own toolbox -- or the different ways to be Fishers of Men.
I've spent a lot of time talking to atheists and listening to atheists. The ones I have talked to in depth rarely argue that God does not exist; they spend the lion's share of their time arguing that God is cruel and unworthy of their respect. Their main argument against the "existence" of God is that he's mean. That's not actually an argument against God's existence at all (after all, it is possible for someone to be mean and still exist); instead, it's an argument against his trustworthiness. The only known antidote to the hatred of God is the message of the cross and the resurrection of Christ. The love and hope in our lives come from knowing Christ's resurrection. It is through Christ's resurrection that God gives us hope: if the grave is a tunnel, then the resurrection is the light at the end of it. Knowing God, knowing that we can trust God, knowing God's love for us: this is the medicine that restores our souls. While the village atheists are full of bitterness that God has abandoned us to lives that are "ugly, brutish, and short", the good news attacks the root of the problem: God has not abandoned us. He has joined us in this world in a life that was brutally and cruelly cut short, suffered badly and from both friends and enemies, and taking on the powers of "ugly, brutish, and short" on the cross, he extinguished the power of hatred and of death and broke down the wall separating God from man. God does not let our lives come to nothing. God is trustworthy. He has promised that he will raise us up at the last day, and has given us Christ's empty tomb as a pledge that our tombs will also be empty, when we will join him in saying, "Where, death, is your victory? Where, grave, is your sting?" That is the message that creates faith.
(To be continued ... I'm wordy enough already!)