Bertrand Russell the philospher delivered a lecture called 'Why I am not a Christian' on March 6, 1927 to the National Secular Society, South London Branch, at Battersea Town Hall. I too am no Christian and while I would not compare my reasons in the same light as such an academic, I do have them.
The sort version is that I was once a committed Christian who accepted Jesus as my personal saviour and prayed regularly. One thing that really began to worry me was the issue of suffering. There was so much suffering in the world. Children born into misery and dying in hunger in pain, I always asked Why? To me there was no point in saying God didn't do it, or it was evil men or even the devil - The god I believed in created everything including evil. He could step in and stop suffering at any time. When I asked the question myself I got the 'God works in Mysterious ways' type of answers. I decided that the God I believed in wouldn't let this happen and started to reconsider my beliefs. I gradually became agnostic and now would consider myself atheist. Stating this isn't to try and de-convert anyone but to me senseless suffering is not something a loving god would allow. I lost my believe in a god because I could not face the prospect that a being exists that can intervene and chooses not to.
Now as a recovering Christian the world without a god in it makes much more sense to me than it ever did when I believed there was one in it.