There are two possibilities. There are no gods, or there are gods. Or one god, if you prefer.
While our perception is limited, our imaginations are not. So it is easy, inside of ones head, to override reality whenever convenient. And making stuff up is a universal hobby among humans.
Now you can get all philosophical and ask if reality is real and stuff, but you can't do that and also make broad statements about how many christians there are, because if it is all imagined, you might be the only one. Since you need backup, I'd think you would be a bit hesitant to dismiss them so lightly.
I'm not the only one who perceives the sun. If i ignore its power on a summer day, I get sunburned. I can get sunburned in the winter, but it is harder. And that is consistent with the known track of the sun across our sky, as predicted using math and science. When I set something on the grass and leave it there for a week, the plants underneath suffer due to a lack of sunlight. The effect is obvious. And when the object is removed, if it hasn't been there too long, the grass and other plants pep right up. Because they again have access to the sun that some say may be imaginary.
Religion, on the other hand, can only point to their allegations that he is real. People such as yourself, Lukvance, can claim to feel him, but that is not universal. And others that do feel a god often feel a different one. Whereas the sun is universal. It will burn you whether you believe in it or not.
So while I've no doubt I could be in some sort of matrix thing thinking I'm sitting in front of a computer typing away, I like to think that if my imagination was the main player, I would not have gone to the trouble of imagining my first Mac, which took almost five minutes to boot up off of floppies. I tend to think I would never imagine GW Bush as president or, even less likely, Cheney as VP. My mind is not capable of going that low, so they must have been real. And if they are real, everything else is too. Albeit in forms none of our minds can perceive with exacting accuracy.
The concept of a god is easy to imagine, but extremely difficult to match up with reality as I know it. The source of the story, the bible, is a multi-interpreted tome which people have killed each other over for centuries. Often times when both sides believed it. And I have a heck of a time imagining an omnipotent god and an incompetent communicator rolled into one. But if people were involved, from conception until today, then it all makes sense in the world. The bible is incredibly consistent with human imagination. It is completely inconsistent with any creator that I would conjure up.
If your god is real, he's incompetent. Or he's set his standards too high for the people he himself created. Or he's been playing too many games and a lot of us have quit. In any case, I've spent over 50 years assuming that he doesn't exist. And I don't seem to have suffered very much in the process. In the meantime, I've watched people who self-identified themselves as good christians (just like you) suffer terribly at the hands of fate. Of course, I've also known good christians who were 97, to that isn't universal either. However, if christians can't agree amongst themselves, can't clearly benefit from being believers, and often can't find a way to convince doubters that their god is real, then it seems to me that it is far more likely that he is not real than he is.
And the fact that there is no hard evidence for his existence doesn't help either.
And by the way Lukvance I know you're impressed with big numbers, but converting 2.5 million new christians a year to a planet that grows by 81 million a year isn't, in an of itself, much of a claim. If you are going to bandy about numbers, you need far more context. Big isn't always big enough.