"There is no Empirical Evidence for the Existence of God"

It's often asserted that "there is no empirical evidence for the existence of God", particularly in comments on science articles. It sounds like a show-stopper. If I'm caught believing something which is not supported by any evidence, I seem to be shown up as a stupid or ignorant person. In this note I'd like to question the assertion, though, using two questions: "who says so?" and "why do they say so?" Lastly I'll raise the question of whether it's really true.

Who Says So?

The first question, "who says so?", is directly prompted by the word "empirical". The dictionary definition of this word is "obtained by observation or experiment". So empirical evidence is evidence which someone has collected by observing things or trying experiments and observing the results. As soon as this is fully stated, the force of the "who?" question is apparent. It's entirely possible that I've observed things or tried experiments which other people haven't. So I may have empirical evidence which others don't, and vice versa! The original statement seemed to have in mind a fixed body of empirical evidence which everyone shares, but in fact the role of the observer is paramount in deciding what has been observed. (There is one exception to this: science. I’ll discuss that exception below).
So, the statement is wrong. The person making it may well mean to say "I don’t know of any empirical evidence for the existence of God", but that's a different and less striking claim. It doesn't rule out the possibility that another person may have some empirical evidence.
What kind of evidence could that be? Really, anything arising from a person's life experience could be included. If I've had a vision of God, heard His voice, had a religious experience, seen a miraculous event or become convinced of miracles on historical grounds, that's empirical evidence for me and it may well be rational for me to put my trust in it and draw conclusions from it. Yes, I must be careful when evaluating my experiences and I may in fact be deluded, but that's simply the human condition. I can't escape being human and I needn't give up trying to respond rationally to what I have experienced. It's also necessary to realise that what's empirical evidence to me will only be hearsay evidence to someone else if I decide to tell them about it.
This relativism may seem hard to accept because in our culture we do have a shared assumption that there is a body of fixed empirical evidence which we should all refer to. This is where science comes in: the scientific method is a deliberate attempt to provide this common body of evidence. In science, evidence is only admitted if it can be perceived by everyone and obtained by experiment repeatedly. Unfortunately there are several reasons why this method doesn't help us with questions about God.
First, it's a feature of the scientific method that God can never be used as an explanation. This is not because all scientists are unbelievers, but simply because the aim of science is to explore the natural world and obtain natural explanations for what happens in it. It's therefore impossible for "God did this" to be a scientific explanation for anything. The fact that it can't be accepted as a scientific explanation doesn't mean that it's false.
Second, the idea of being able to distinguish between the action of God and natural phenomena is a strange one. If God is the creator of the universe, everything must be ultimately ascribed to Him, not just miraculous happenings. Some scientists are moved to believe in God because of their discoveries while others see no need to take that step; this needn't be surprising.
Lastly, the empirical nature of evidence obtained through science is not always as strong as we think. Yes, in principle anyone can go and repeat experiments by Galileo, Newton, Rutherford and other famous scientists. In practice, though, most of us never do! Even for practising scientists and technologists, there are limitations of time, money and interest which cause us to learn our science from books instead of going back to first principles, thereby putting our trust in the authors of those books. Our "empirical" scientific evidence actually turns out to be mainly hearsay! Again, this doesn't actually invalidate science, but it has to be recognised as being a real part of our human situation.
An overall conclusion from these considerations is that empirical evidence doesn't really have the supreme authority implied by the first claim. One person may have empirical evidence which another does not. Certain evidence may be empirical for one but only hearsay for another. Much evidence which we think empirical isn't really, at least in our own experience.

Why Do They Say So?

What, then, about the second question; "why do they say so?"
In the discussion above it was noted that it would be more reasonable for someone to say "I don’t know of any empirical evidence for the existence of God". But this is hardly ever said. Surely it can't really be the case that people who make the claim about empirical evidence don't actually know what "empirical" means and haven't realised that it differs from individual to individual?
What seems to be going on here is an attempt, for unstated reasons, to make a claim stronger than is really justified. "I don’t know of any empirical evidence for the existence of God" is a reasonable statement if it's true in the speaker's experience. But for some people, saying "there is no empirical evidence for the existence of God" is much more satisfying! There seem to be two kinds of atheists typified by these two statements. One kind doesn't believe because they see no reason to; they see no likelihood that this will change but if they have an amazing experience in the future they might reconsider. The other kind doesn't believe, is determined not to believe, is angry that others do believe and chooses to belittle the rationality of believers by making the ill-founded assertion. It's hard to accept that this is always just a mistake, and it seems to say more about the attitudes of the speaker than about what can be known empirically. For such a person it's not surprising that they have no empirical evidence; they certainly won't have thought it worthwhile to seek any.
It seems that the word "empirical" has been over-used. If it's not a supreme authority because it varies from individual to individual, maybe I shouldn't use it as the only authority within my own thinking. I need to be aware that I might be deluded, or I might have made a mistake. At the same time, I am forced by my human limitations to consider and evaluate more indirect kinds of evidence. To reject everything except what is empirical in my own experience will confine me all my life in severe ignorance.
In fact, if I want to be able to discuss the existence and nature of God with others, I find that I actually have to avoid offering too much of my own experience. I may find it immensely convincing if God has worked in my life and revealed Himself to me, but I'm not able to convey that kind of evidence to others. Instead, it's necessary to appeal to shared knowledge such as the reality of sin and righteousness, the content of the Bible, the historical evidence that Jesus really rose from the dead, studies which find that churchgoers are happier, healthier and live longer and the appearances of God's work in people's lives. I might also recommend that they experiment for themselves, asking God to intervene in their lives and waiting to see what happens.
This might lead others to think that my reasons for belief are weak and find the fact that I do believe strange. In that case it's necessary to point out that I'm only offering the kinds of evidence which we can share. Of course I think I have empirical reasons for belief too, but I'm unable to transfer those reasons directly into the awareness of another individual. All I can do is pray that God will reveal Himself to them too.
In the end, if someone wishes to assert that "there is no empirical evidence for the existence of God", the only reply I can make is, "For me, there is!"

So, Is There Any?

But maybe that's a bit defeatist. So far I've stopped short of saying why I think it is reasonable to believe in God because I wanted to discuss the "empirical" remark in isolation. But if we're capable of discussing this at all, surely we should be able to jointly consider at least some evidence? So I'll briefly lay out some evidence as I see it, bearing in mind that this isn't the only evidence there is, only a small sample of the sharable kind:

In spite of modern thought, people generally have an awareness from the world we live in that there is a Creator, and they want to know Him. It actually takes some effort to suppress this tendency. It's "built in"; why?

The Bible
Although it's a collection of books from a long span of time, it all hangs together; the New Testament fulfils the Old. The things it says about human nature are true: we all aspire to moral standards but can't even live up to our own standards, let alone God's.

The documentary evidence that he rose from the dead is so strong that historians would accept it as a real event except for one feature: it's a miracle. We believe things about Julius Caesar and William the Conqueror on less evidence.

It works
Recent studies have found that churchgoers are happier, healthier and live longer. Great efforts have been made to remove possible sources of bias, such as churchgoers tending to be people who avoid risks and make healthy choices, and still the effect remains. It's of about the same magnitude as the effects of smoking. It's been pointed out by doctors that if Christianity was a drug the Department of Health would want everyone to take it because of the savings for the NHS!

It changes people's priorities
As should be expected, Christians are more caring and compassionate. There are exceptions (some people are hypocrites), but the trend is clear. Many social advances in our society have been brought about by Christians in the face of secular opposition (Elisabeth Fry; Florence Nightingale; William Booth; William Wilberforce). Today you can tour the world and find many Christian medical missions, but fewer of other faiths or secular organisations. Many now-secular charities were founded by Christians. (And nominally secular charity works often turn out to be staffed by Christians).

Lives are changed
One can read numerous autobiographies of people brought out of degradation and despair, freed from addictions and given hope; all, according to their account, by the power of God. On a personal level, I find that Christians I know are more caring and contented, and they deal with problems better than others.

That's empirical evidence; anyone can check up on it. Maybe it's not strong enough to convince some, but that's another question. Someone who says "there is no empirical evidence" is therefore either ignorant or being dishonest.