The reasons are simple:
1) Almost everyone, at one point in their life, has questioned whether or not God exists.
2) I don't know the answer. I know what I believe, more or less, but I don't know the answer.
The Question ~As I mentioned above, most of us go through a period where we question God's existence, or even deny it completely. I did, for many years. I still do. I have questioned the validity of the Bible. Is it truly correct? And is it complete? I, like so many others, will watch something horrific on the news, and wonder "How can there be a God for this to happen?" I remember thinking this on 9-11 as planes destroyed our towers and took innocent lives. I recall thinking this just weeks ago when someone walked into an elementary school and murdered 20 first graders.
And of course the questions don't stop with Is there a God. Once we believe that ok, maybe there is one, the questions just keep coming. In fact, more questions may come before you even determine whether or not you believe. For example, I grew up being taught that God is omnipotent, omnipresent, and omniscient. Ok, so he's all powerful, is present everywhere, and knows all. I also grew up being taught that God is good. Ok, so if God is good... wouldn't he not allow bad things to happen (and he does know bad things will happen... he's omniscient after all)? Can it be that the fact that he does allow bad things to happen is that he is not all powerful - he isn't capable of changing things? See what I mean about the questions just coming like crazy? One simple question - "Does God Exist" - can quickly be turned into dozens of additional questions.
I don't think there is anything particularly wrong in questioning it, so long as we do so intelligently. If we're going to question, we must be willing to accept that there is a chance he does exist. We must be willing to keep our eyes open to the possibility. We must learn and read and study. We must seek the answer through our science book and through our Bible; but, we must not be afraid to simply have faith that he does exist, and stop questioning this fact.
The Answer ~When I ask any question, I want an answer - a factual, indisputable answer. I don't want the gray area - just black and white. Unfortunately, when you ask someone to provide proof of God's existence, that person will often refer you to the Bible. Now, I'm not sure if anyone else sees the flaw in this "proof"... but in my opinion, IF there is a God, than yes, you can refer to the Bible. However, if there is NOT a God, than the Bible is also fiction. Therefore, you can't use the Bible to prove or disprove anything.
The other "proof" many will offer is the perfection of the universe. Our planets are beautifully round and float around a sun which provides us with the perfect amount of heat. Everything needed to sustain human life can be found here on planet Earth. Man has a complex brain. Naturally, none of this could have happened in any scientific way. It had to be God. Again, this is a bit of a flawed "proof". We do have proof of science's involvement in creation/evolution. And this proof is through scientific research - not a myth passed down from generation to generation.
I don't have the answer. I have all the questions, but none of the answers. All I know is that in my heart and soul, I do believe there is a God. Yes, I will continue to question the intricacies of religion, but this questioning and researching does not mean I am turning from God. I am simply trying to understand, rather than blindly believe (and not truly even sure what is believed). So, for a completely opinion-answer...
Yes, God does exist.