I believed. For five years in a Christian secondary school I believed - followed by an iffy two years in college (where I finally picked up swearing, drinking and sex). Now, after watching the Zeitgeist, and also gaining the courage to question my beliefs (afraid of being thrown into Hell for disbelief), I am really not so sure.
I haven't personally witnessed any miracles, but I have heard a number of stories from friends and teachers. The one thing that is quite convincing, is the phenomena of Christian tongues. There were two or three girls in my year back in the GCSE years that were able to speak in tongues, and they are not the type to lie and blurt out random noises to convince people of God.