I have reason to believe both. I'm pretty sure that many who claim to doubt God without entirely disbelieving are simply following their emotions. Complete disbelief is usually because of how that person was raised, or because they saw the evidence in favor of atheism. Those who believe in a God, I believe, do for the same reasons. I'm inclined to think that those who sit on the fence are simply wrestling emotions.
And how many of them can be true? One. They all contradict each other morally and otherwise so they cant all be true. Being that more than 99.9 percent of religios have to be made by man why should i believe in any of them when one doesnt stand out amongst the others like you would expect one to if it were made by god. Seeing the work of god and the work of men would be like seeing the work of a famous writer compared to the writings of a special ed kid. And no religion stands out amongst the others like you would expect it to if it was created by god. The bible doesnt stand out amongst the other religions so i cant believe in it for that and for many other reasons. The bible claims gods perfect while it says he tortures children for the sins of their parents. No one thinks a child deserves to be punished for its parents sins which it had no control over. But the christian god does. Also if there was a god (an all powerful authority member) then why are people allowed to do whatever they want. Any good human would stop evil if they had the ability to do so but a perfect all powerful god lets everything that happens happen? Whats wrong with that picture? We call him perfect while he does things that humans would be called evil for doing. If god created me and put me here to suffer for the disobedience of my ancestors (adam and eve) then its not my fault i dont believe. He shouldnt have claimed to be perfect if he does stuff like this.
With so many seeming impossible things happening in the bible, it is easy to see how some may question it's truthfulness. Many people who read fiction or watch fantasy movies notice how fantastic things tend to be make-believe and not true to fact. Often, people see a similarity between known works of fiction and the bible and at least start to get the idea that the bible is just a work of fiction.
Some others may take a scientific or logical approach. Example: Even though I was a Christian, I never believed in ghosts. One day, a friend asked my why I didn't believe in them. I explained the reason using science and logic. Later, I did the same with other things like vampires, werewolves and such, then one day did the same with the idea of gods.
It would also be common for people to doubt for emotional reasons. Some may feel the loss of a loved one as pointless and feel that if God was real then he would not have taken them. Usually this is only temporary and they return to their faith out of hope that the loved one is in heaven. I would guess the strongest bond with a religion is emotional. Though a person may feel they can dismiss faith logically, emotionally they have a hard time accepting life to be finite. That after they or a loved one dies, they cease to exist. The idea that we have some all powerful being who can help us through hard times or the idea that our good deeds will be rewarded in the afterlife is hard to let go.
The vast majority of those who hold no religion to be true have come to the conclusion that the religions in question are logically false.
There are others, of course, who do not believe in God or the Bible on an emotion basis (such as believers of other exclusive religions for example.)
Belief in any unprovable, unknowable, and easily doubtful entity is ALWAYS emotional.
Doubt in such a being is not only rational, it's completely reasonable.
Belief on the other hand...
The reason the non-believers may appear emotional to you could be the fact that they just don't understand how facts so obvious can be straight out denied by the Christians.
I've talked to countless Christians and have tried to understand their logic and here's what I've came up with..
The reason why the messages aren't getting through to them is because the Christians are using the Bible as base for their belief instead of facts that are repeatedly challenged overtime for verification. Now that sounds like something we all know doesn't it? But it's not as easy as it sounds. It's as if saying for the Christians the apple only comes in gray, while for the non-believers, the apples comes in red. It's the same apple but the Christians and non-believers see different colors. The apple will serve as the basis for how the world constructs itself. For the gray apples, the sky will eventually be red and for the red apples the sky will be blue. Then in the end, no matter how hard the non-believers argue it has no effect, because the apple will always be gray to the Christians. If the non-believers are to convince the Christians the apple is red they'd have to convince that the color is an illusion caused by the color-blindness they have. They see the "truth" but just from another view.
Now to get through that barrier is no easy task. If you as a non-believer is truly dedicated to saving the Christians I would recommend taking a different approach than the ones that are being done right now. I personally think religious nuts are lost causes and should be in an insane asylum and there's no need to waste time on trying to convince a color blind that the apple is red. Believe me, I've tried. But if you're one of those who's willing to keep going you have my respect.
The bible makes huge claims that just cannot be supported and conflict with the natural world. To rationalize the bible is to either edit it down to basic suggestions on how to live that can already be discovered by looking into your own heart, or to disregard it completely. I find the religious WANT it to be true, and emotionalize these hopes in every aspect of their lives they find in need with help from a "higher Power." Which in turn again, simply isn't rational.