When asked what he would say if he met God in an afterlife Bertrand Russell responded, ‘I should reproach him for not giving us enough evidence.’ Some atheists will make the stronger claim that there is no evidence for God’s existence. By contrast, on this website we claim in various articles that there is evidence for God’s existence, and pretty good evidence into the bargain. Given such a disparity, it is worth asking what we mean by ‘evidence’?
Some people might think of evidence in terms of the five senses, but this is much too restrictive. Scientists, for example, don’t limit themselves to the five senses, but use various instruments to weigh objects, measure charge, detect particles, etc. Of course, the senses are important since, for example, we see the dial pointing to a certain value, but we don’t see the weight of the object or see the particle in question. Obviously though, we can’t use instruments in this way to detect God, so if this is how evidence is to be understood the evidence for God seems to be non-existent.
But this is still much too restrictive because it suggests that the only way we can know if something exists is to detect it directly using either our senses or suitable measuring devices. The problem is that things in science aren’t so simple. How do we know that particles such as electrons or protons exist? We certainly can’t see them with the naked eye. Scientists have developed various particles detectors, but how do they know they are really detecting the particles as claimed? It’s not as if they can take a look to check that the devices are getting it right. The story of how scientists came to believe in the existence of such particles is not straightforward, but very roughly the idea is that postulating their existence made much more sense of a range of phenomena that otherwise would have seemed very puzzling.
When we consider historical claims in science, things are even less straightforward. Many scientists believe that the dinosaurs were wiped out by an asteroid collision in Mexico about 65 million years ago. What evidence is there for this belief? Clearly, this conclusion is not one that can be reached directly using the five senses or some sort of instrument. Instead, in 2010 an international panel of scientists investigated the matter in great detail by considering all the available evidence and comparing the asteroid collision theory with alternative explanations, particularly one appealing to volcanic activity . Basically, the asteroid collision theory explained all the relevant evidence much better than the alternatives.
Similar principles apply in non-scientific contexts. Historians draw on a variety of sources, but they do not simply describe these sources to us. Instead, they go beyond them in order to make sense of them and to come up with historical narratives that best account for all the available evidence. Detectives similarly do not have direct access to the crime itself in the vast majority of cases. They attempt to piece together all the evidence in order to determine the most plausible explanation.
When it comes to evidence for God a similar approach seems sensible. Various features of the universe constitute the evidence and the question is whether God’s existence would help us make more sense of this evidence than alternative viewpoints. In particular, in comparing theism with atheism, does the existence of God provide a better explanation of the evidence than the view that physical reality is all there is? On this website, you will find articles attempting to show that the existence of God helps to make better sense of the existence of the universe, the beginning of the universe, the order of the universe, fine-tuning of physical constants, consciousness, morality and other things as well. It is worth making a few general comments about how we weigh the evidence.
First, insofar as belief in God makes better sense of various features of the universe, these features provide evidence for God (and against atheism) . Indeed, the idea that there is evidence for God can easily be accepted by atheists. Atheists could try to argue that overall the evidence is not sufficiently convincing .
Second, the case for the existence of God does not depend on any one of these features of the universe providing a convincing case for God on its own. Some will claim that one or more do achieve this, but that is not necessary. Perhaps a number of features will provide some evidence for God, but it is only when they are considered together that the case becomes strong. This can also happen in a detective scenario. Perhaps no single piece of evidence, considered in isolation, shows that Jones is guilty, but when the cumulative weight of all the evidence is taken into account, the verdict becomes clear.
A related point is that some of the features of the universe considered might provide much stronger (or weaker) evidence for God than others. For example, some people will not find the evidence of consciousness convincing, but perhaps it still adds some weight to the overall case.
A lot more could be said about evidence in the context of the existence of God, but the point of this article is really just to say that the evidence should be considered on its merits. Statements about science being based on evidence whereas belief in God is based on faith or dogmatic claims that there is (or could be) no evidence for God are really just tactics for avoiding the difficult task of evaluating the evidence in detail .
 Richard Dawkins offers a general argument against the idea that God provides an explanation for various features of the universe such as fine-tuning. He claims that God would be even more in need of explanation than the things he is supposed to explain. For a response to this argument see the article There’s Probably No God – a response to Richard Dawkins.
 They might also argue that the existence of suffering and evil is evidence against the existence of God. Believers in God could offer various responses to this argument, but just as atheists need not deny that there is some evidence for God’s existence, theists need not deny that there is some evidence against God’s existence. The theist could still argue that overall the evidence supports belief in God.
 For a detailed article on the nature of evidence see Tim McGrew, ‘Evidence’ in The Routledge Companion to Epistemology (Routledge, 2010), a version of which can be found at http://homepages.wmich.edu/~mcgrew/Evidence.htm and for a detailed approach to evidence for the existence of God see Richard Swinburne, The Existence of God, 2nd edition (Oxford University Press, 2004).