According to the Pew Research Center, while "the vast majority of Americans still believe in God ... there are strong signs that many are less certain about this belief than in years past." Pew's research is dependent upon what is known in probability theory as "The Law of Large Numbers," which states that, given a large enough number of trials (in this case, surveys), the results will be close to the true value.
Pew's research requires interviews with thousands of people to obtain a result that is representative of the general population. But what if, rather than asking 1,000 different people about the state of their faith, they were to ask the same person about the state of his or her faith 1,000 times, say over a period of ten years?
I suspect that there would be times when the person was "absolutely certain" (to use Pew's language) of God, and other times when he or she would be less certain, or perhaps even doubtful. Such a result would be in line with our experience of faith and the complexities of being human.
Humans are, from a Christian theological perspective, complex. They are multifaceted or, more properly, multilayered. Humans don't just have bodies. They are bodies. And yet, they are more than their bodies. They are also mind. But they are more than their minds; they are also souls. And soul itself is transcended in spirit. Each human being is, as G. K. Chesterton once described the Church, "larger on the inside than ... on the outside."
What this means, when it comes to faith, is that a person's confidence in God (or at least his or her awareness of it) can increase or decrease in certainty, depending on where the person is in his or her development. That person's development depends in turn upon a great many factors, not least of which is God himself.
Because people are multi-layered, a person can believe one day and doubt the next. But that's not all: he can do both almost simultaneously. He can be traveling the highway of faith one moment and fall into a sinkhole of doubt the next. That sinkhole, however, is not something outside himself, but a place in himself where faith has not yet developed.
The classic expression of this is found in the Bible itself. A concerned father brought his ailing son to Jesus and pleaded, "If you can do anything, take pity on us and help us." Jesus responded, "If you can? Everything is possible for him who believes."
"Immediately the father of the child cried out and said, 'I believe; help my unbelief!'"
There can be no doubt that the father's faith was real, but almost in the same moment he appeals for help with his unbelief, which was also real. There was room in the man for both, and there were significant patches of his interior landscape where faith had not yet taken root and grown.
As someone who has been privileged to accompany people on their spiritual journeys, I've seen the same kind of thing happen many times. Our experience of faith is not static but dynamic. We are not human beings exactly (at least, not yet) but "human becomings." From where we look out of ourselves today we may not see God, but if we travel a little further in our "becoming," we will. While the discovery of areas of unbelief can be troubling, it can also be helpful. It allows a person to choose faith, to act on it, and see it grow.
The dynamic nature of belief is not only exhibited in religious people, but in all people, even atheists. Around the next corner on the highway of doubt a solid rock of belief might be blocking the way. Elizabeth King provides a good example in her Washington Post article titled, "I'm an atheist. So why can't I shake God?" Likewise, David Bowie described himself as "not quite an atheist... There's a little bit that holds on." Even Richard Dawkins runs occasionally into those places where his doubts are cast into doubt.
That's the nature of being human. But it is the nature of God to help humans to believe even in the midst of their unbelief.