Many people say that they would believe in God if his existence where more obvious, but it isn’t so they don’t. Some offer this a personal explanation for their own disbelief while others go further and use it as a basis for an argument against the existence of God. According to this argument, if God exists he would want everyone to know that he exists and would be capable of bringing that about by making his existence more obvious. But since that isn’t the case, it follows that God doesn’t exist after all. This is known as the argument against God from divine hiddenness.
One point that’s worth highlighting at the outset is that there can be good evidence for things that are not obvious. It isn’t obvious that the Earth goes round the Sun, but there is evidence for it. Similarly, it isn’t obvious that solid objects such as tables consist of mostly empty space, but the physicists tell us there is good evidence to believe that this is true (note that sometimes people confusingly, and wrongly, think this means that tables aren’t really solid). So even if God’s existence isn’t obvious, there could still be good evidence for God. Many will claim that there is little or no evidence for God, but sometimes this is because of a very restricted conception of evidence that restricts it to something like experimental evidence. If we think about evidence more broadly, arguably there is good evidence for God.
Another point is that the objection assumes that ‘if God exists he would want everyone to know that he exists’, but is that really true? This raises a question about God’s interest in us. The philosopher Paul Moser argues that as a perfectly good and loving being, God would not merely be interested in our acquiring an abstract knowledge of his existence, but in our moral transformation. From a Christian perspective, God wants us to know him personally. So, while it’s true that God could ensure that more people know that he exists by making his existence more obvious, it’s far from clear that this would result in more people coming into the life-transforming, loving relationship that God desires for us. In fact, from a biblical perspective it seems clear that in some cases people reject God even though he has made his existence obvious to them (e.g. to the Israelites in the Old Testament or the religious leaders in the New Testament in response to Jesus’ miracles).
Our attitude can be very important when it comes to acquiring knowledge about God and this is particularly true when it comes to the personal, and not merely abstract, knowledge noted above. This might seem odd. Surely it is the evidence that is important, not our attitude. However, our attitude can affect what evidence we are willing to consider, how much effort we’re prepared to put into finding it, and how we go about evaluating it. This is true in other areas too. In science, for example, many discoveries would not be made were it not for a painstaking approach on the part of the scientists to carry out numerous experiments or develop more advanced mathematical models, or to be willing to look at new lines of inquiry. In human relationships too, our attitude towards other people can have a huge influence on getting to know other people. Loving relationships cannot be formed without openness to the other person and willingness to put effort into developing the relationship.
Some atheists are quite open about the fact that they don’t want there to be a God. Others demand evidence of a very narrow kind that seems to amount to either mathematical proof or something akin to the sort of evidence that might be acquired in an experiment in the science lab. Those who adopt such an approach tend to be very dismissive of reasons that are offered in favour of God’s existence and in many cases they aren’t prepared to put any significant effort into understanding these reasons or evaluating them with an open mind. Now, my point is not that all atheists approach the topic in this way, but just that for those who do, merely providing more evidence for God will be unlikely to change their minds. Why? Because their attitude to God and to the possibility of evidence for God virtually guarantees their atheistic conclusion.
So what sort of attitude is needed when it comes to knowing God? Jesus emphasizes the importance of humility. For example, he thanks is Father that he has “hidden these things from the wise and learned, and revealed them to little children” (Matt. 11:25). His reference to children also draws our attention to the relationship with God – knowing God is more like the relationship between a child and parent than knowledge of abstract facts. Jesus also highlights the value of God’s kingdom (Matt. 19:44) and the need for searching on our part (Matt. 7:7), a point also made by the prophet Jeremiah, “You will seek me and find me when you seek me with all your heart” (Jer. 29:13). 
Or as the French mathematician and philosopher, Blaise Pascal put it, “[God] so regulates the knowledge of Himself that He has given signs of Himself, visible to those who seek Him, and not to those who seek Him not. There is enough light for those who only desire to see, and enough obscurity for those who have a contrary disposition.”
Consider this question: if there is a God, could my approach be inappropriate and prevent me from ever believing in God? As in science and human relationships, having the wrong attitude and approach to God can prevent us from acquiring valuable knowledge. Adopting the sort of attitude suggested by Jesus and the prophets doesn’t require us simply to assume there is a God or to set aside critical questions, but it does suggest that we need to look at our own attitudes and motives. In a very helpful booklet on the topic Why isn’t God more obvious?, Paul Moser suggests that the “question suffers from a misplaced emphasis” because if there is a God perhaps the question should be “Why do we fail to apprehend God’s loving reality and presence?”. He suggests that “we do well to look at ourselves rather than blame God”. Perhaps if we adopt the right attitude, so that “our hearts are willingly attuned to God’s self-giving transformative love, God will be obvious enough.”