I am going to start out with a statement that may cause some of you to scratch their heads: Many Christians believe the same things about God that many atheists do.
The problem is that western theology tends to build God-constructs–that is, a set of definitions about who God is. We can look up “God attributes” on the interweb and find many different lists of things that supposedly define who God is. And then, of course, there are images of God from the Old Testament that curiously don’t look much at all like Jesus. What you then have is a God-construct. Not God, but a mental golden idol that takes the place of God. In other words, a God who isn’t, which makes this god substitute easy to not believe in.
So again, many Christians believe in a God-construct that many atheists can’t believe in. (Many athests will say “I don’t believe in any god,” but I have a hunch that at least in the Western world, their mental image of God looks a whole lot like this God-construct.
The Eastern Orthodox church (which is the best reflection we have of the early church) uses something they call apophatic theology, which is focused on defining who God isn’t. In the West, we are obsessed with definitions and categories and boxes. If we don’t have a box to put something, we must create one, as soon as possible. It’s makes us nervous to have something that can’t be defined or contained in some kind of human construct.
Rather, the Eastern Church recognized centuries ago that to try to define God is to create heresy. God is simply bigger than our human ability to understand. For example, any attempt to define the concept of the Trinity will always result in heresy. It’s easier to specify what the Trinity isn’t, which then leaves room for a lot of unknowns–better known as mysteries.
So, the answer to questions like “how can one God be three persons?” is best answered by saying “I don’t know.” We can say that they are not 3 separate Gods, we can say that God the Father didn’t become Jesus which became the Holy Spirit, and so on, which rules out some heresy while leaving plenty of room for mystery.
I believe in a God who isn’t capricious. I believe in a God who isn’t angry with us. I believe in a God who isn’t… well, you get the idea. Atheists may still not believe in God, but at least they will not be distracted by disbelieving a false god-construct. And maybe we can start believing in a God who is, mysteries and all.