Now for all the scientists out there this is not a question of proof or anything along those lines.
For my part I choose to believe in a God because I honestly believe there is one (though I did start doubting for a little while) I've always felt that there was more to our existance on earth - and that doesn't stem from me wanting to live forever or as a spirit, as I don't even know if that will happen.
I also believe in him because many many times when I could not carry on, on my own strength, I managed to pulled through. I also have had some personal experiences which have made me sit back and think.