The modern world is a product of the enlightenment, the scientific revolution. In science nothing is accepted as true until it has been proved beyond a burden of doubt. Until strong evidence is found, verifiable, recorded, replicatable evidence, nothing is true.
Yet before evidence was recorded, verified, replicated, was the truth untrue. Did the act of observation give substance to something which, before science described it, was a pack of lies? Did evolution for instance exist before Darwin wrote his book? If Darwin had demanded proof before he spent considerable money, time and effort investigating his theory, he would have never left England. He, like all scientists, needed to make a leap of faith, to invest himself in a theory he had faith in, but no evidence, in order to see if it worked. He had to do this before he knew for sure one way or the other. It was only after living his life in pursuit of evolution that he discovered evidence to support his faith. The scientific revolution has led many people to demand evidence before acceptance, but this is a fallacy. If we refuse to first proceed on faith this severely hampers us and our understanding of the world.
And what about things that cannot be proven? Things that are historical, or not present right now. Before I got married, I wondered, would my wife always love me. Would I always love her? I knew we loved each other now (or we had evidence to believe we did), but what if this faded and died a few years down the line. We would have made a terrible mistake. We could not prove it one way or the other, neither of us could tell the future, neither of us had been in love before, to know how our experience of this emotional state developed over time. But we had to make a choice. We could have demanded proof before proceeding. But this would have meant not getting married, since no proof is possible. We chose rather to move forward in faith. In faith that our love would continue, that our relationship would weather storms neither of us could foresee. Even though our relationship was young, and barely tested yet.
A person may demand proof before they are willing to believe in God, in the claims of Christianity. They may choose not to proceed, not to investigate further, until sufficient evidence is presented as to overcome their natural doubts. But this means choosing not to move forward towards an understanding of God and Christianity. Since no proof is possible. The only thing that can prove Christianity to an individual is the lived experience of it. Another person can relate their experience of Christianity, but this is not evidence, it is subjective experience, easily dismissed. The claims of Jesus and the Bible are historical, from a time when peer-review, recorded evidence trails, and double-blind studies were not carried out very regularly. To demand proof is to demand something that does not and cannot exist. To refuse to believe until sufficient proof is presented is to refuse to believe. And this fatally hurts us, and damages our understanding; of the world, of us, and of God.