Which one? There are many Gods in this world. I cannot say for sure that I believe in the God of the person who is asking the question, unless, this person, first, tells me who God is, for him or her.
Yes, I believe that I am a created being and therefore there is a creator, someone who gave life to humanity on the onset. I also believe that the earth and the whole universe was created by a being who was capable of planning and executing a very complex creation.
Why do I believe?
I was born that way. I believe before I was conceived. I have the feeling that my ancestry, for many generations, were strong believers in a Christian God, therefore the whole spiritual atmosphere surrounding me from the start.
I never wavered in my belief in God, but I did modify it as I grew. My own thoughts, reflections, spiritual life gave me a different understanding of who God is, his motivation for creating, and his way of thinking and loving. So, the God that I believe in today is not the God that I was born to know. So, if I was asked by someone from my Parents generation who believed the way they did if I believed in God, I will have to say, no, I do not.
So far, the best definition of God that I have come across is this one:
God, the Creator of all things under the sun, is the true parent of all humanity. He is not a parent in the parochial sense, existing only for a certain religion, a certain race, or the residents of a certain region. You may call Him by any name, be it Jehovah, Allah, or any other. What is important is that He certainly exists, lives as the true parent of all people, and is carrying on the great work of Creation. He governs everything in the universe, and He carries out His providence through history in accordance with the principles and laws of nature that He set up at the beginning of time.
[Rev. Sun Myung Moon, April 10, 2006, Peace Message # 3]