What religion should people adopt if there is uncertainty about the existence of deity? If there were only one choice, to believe or not in a god, the choice would be rather simple as Pascal's wager taught us: believe in the god just in case he turns out to exist. Things become a bit more complex if one has also to choose in which god to potentially believe. First, the fact that they are multiple candidate gods means all but at most one may turn out to be frauds, and choosing the wrong one may have serious adverse consequences. What to believe then? Luckily, economists have you covered.
Tigran Melkonyan and Mark Pingle use decision theory to come to the conclusion that agnosticism, which is to not take a stand, is an optimal choice if any combination of the following hold sufficiently strongly: 1) in-life benefits of agnosticism are higher than "other" religions, 2) the after-life benefits of agnosticism are not too much lower, 3) none of the religions is very likely to be correct, 4) life is not too long or too short, or 5) transition costs from agnosticism to a religion are lower than between religions. These all make intuitive sense, except the fourth, which has to do with the fact that if life is short, you want to believe in a god right away. If life is still expected to be long, you want to believe in no god. Agnosticism is in the middle, where you postpone a choice when you can afford to do so.
It would thus seem that many more people should be agnostic then there are (1-10% in the US). Why so? I would think this has to do with the fact that we do not make such choices from a clean slate: we are conditioned by the environment we grew up in, and kids are easily impressionable. Once they have been told to believe in a particular god, switching to agnosticism is very difficult: you face the disapprobation of the immediate family and peers. But their is also the fact that in any situation, it is very difficult to change the opinion of a person, even if the person is wrong. We are all conditioned that way, and while we easily adopt a first opinion, we rarely change it. This inertia will keep agnosticism, and atheism, a minority in the US for a long time still.