In short, 'we don't think so'. Not the answer you were expecting? Read on...
It is only really since the 17th and 18th centuries, through the late Renaissance and Enlightenment periods, that the Church felt the need to prove God's existence in the face of scientific exploration. Ideas that could not be proven using laws of physics or rational logic were called into question. For not only did thinkers like Luther, Galileo and Bruno challenge ideas like church authority or the workings of the solar system; they had laid the foundation for future generations to demand proof in exchange for allegience to what had previously been assumed to be true.
For in the great span of human history, the idea of proving the existence of God or gods was not a European concept, nor a concept for many belief systems across the world. If anything, the only 'proof' people looked for in faith was of which god was the most powerful, as the idea that some sort of divine being existed was a basic assumption in numerous cultures.
"How do you know that God exists?" is neither an uncommon or unreasonable question to ask of Christians, or indeed to ask of anyone who preaches a religious doctrine as fact. And, frustrating as it may be for Christians, agnostics and even atheists who are looking for a robust debate, few - if any - answers to these questions can be given with any certainty.
A Range of Responses
There are a number of ways that Christians have attempted to respond to this question, all of which have their critics. Click on the PDF window to the side to see an outline a few of the main approaches, before reading below for how we tackle the issue.
At BreadBytes we prefer a more nuanced theological conversation.
In the world of the internet, many discussions on this topic slide into mud-slinging conversations. In the worst examples of discussion forums, those who defend Christianity and those who don't both argue that the other side is intellectually inferior, dishonest or incompetent. Richer, more nuanced participation is therefore discouraged.
From our perspective, yes, God exists. Because we are concerned with theology (knowledge of God), this is a foundational concept that will be assumed throughout this site. However, we also concede that God's existence can't be proven. We maintain that the essential element for understanding the existence of God is faith. Faith represents an alternative means of knowing to that of scientific proof. As faith is not a science, using scientific reasoning to define faith is not a constructive exercise. That can be debated, but we won't do it here: there are plenty of other spaces on the internet to argue about those things.
This does not mean that we are excused from using our intellect in the 'thinking through' and 'application' of faith, but instead serves as an acknowledgement that finding a scientific answer to questions about God will always encounter roadblocks. The eleventh century monk St Anselm of Canterbury described the journey of theology as "Faith seeking understanding". Faith leads us into our quest for understanding God. We hear and encounter God through faith, not through scientific discovery (although such discovery may shape and form the way that we 'do' faith). Interestingly Paul's Letter of 1 Corinthians (12:9) talks about the way that some people are given the gift of faith. Precisely what this means is not clearly understood, other than to say that faith may come more easily to some than others. At the core of our faith here is the person of Jesus. We believe that Jesus is the best image we have as to the character and personality of God. (See more of this discussion on the question page "What is God like?")
Throughout History, intelligent and capable people have both accepted and rejected the possibility of God's existence. Good people have accepted and rejected the possibility of God's existence. Evil people, too. Faith therefore is not a question of intelligence or morality. For this reason, BreadBytes disagrees with traditional Christian doctrine that implies that your faith defines your status in the afterlife (see below for our engagement with questions on sin, suffering, evil, Heaven and Hell). So we won't try to convince you God exists here - plenty of other spaces will do that, and we believe that God is capable of doing that all by God's-self, if necessary!