As someone who spends rather a lot of time thinking (compared with those who work, go to school, or you know, have a life hehe) God is a popular subject. Ever eager to find proof of GOd since the idea's very attractive, and the more likely reality of no gods rather sucky, I think I found a way to believe in God.
When you think of "God" something comes to mind does it not? You don't ask the one mentioning it, "What's God?" You know what God is. Therefore it exists. Everything exists in this way since ultimately everything's just thought and electrical impulse leaping from one neuron to the next. But even in the physics-sense, no matter is in fact solid. It simply appears solid. But when you look at htings under microscopes it's just an atom with a nucleus in the center, and lots of empty space. Interestingly, if you could 'zoom-in' infinitely, you'd always get another dot in the middle surrounded by empty space. Physics puts an artifical stopper to this fact called the Planck Length, but conceeds there's no actualy limit. Can always remove a fraction of a whole unit and go smaller. For this reason, we are quite literally thought (since we're not made of anything but infinitely smaller units of mostly empty space, or as I Like ot think of it, happy thoughts and fairy dust.)
For God to exist, you only need have an idea of what God is. Disturbingly, everyone you know benefits from this fact as well as God. We can't actually prove anyone exists including ourselves as every proof we may use is merely the result of our thoughts and misunderstanding of physical reality.
Does God exist? Yes. Or more specificly, mine and your idea of God exists.