Welcome. I don't believe in ghosts, and yet I feel me and my friends had a ghostly experience...prepare for a long story.
<spoiler=Click for the long story>So my friend does this computer work for this church, so they gave him a key for it. Now, we're ass holes so we thought it'd be funny to have a seance in it one night. It was 2am on a monday and there was about 7 of us having the seance. We set up candles in shapes of pentagrams and put on some Aphex Twins for some ambiance, sat around a table and did the worst job having a seance. It was just us fooling around pretending to have a seance.
When we grew bored of that, we walked around the church in groups just checking stuff out. The basement was really creepy actually, since the lights didn't work, and there was a mirror at the end of the hall which could barely be seen but would look like there was eyes or a figure staring at you from the end of the hall. Besides that, we finally got bored again and met up in the main hall of the church, when Martyn (the guy who had the key to the place) said there was this attic in the church that was supposedly haunted.
We went up to the attic but the door was jammed. Apparently it was nailed shut after someone hung themselves in the attic and his body fell on the door somehow, and it took months to find him. This somehow meant that he was haunting the church. They currently use it for storage, and the priest apparently (I say apparently for a lot of this because this is all what Martyn told us) didn't allow anyone into the attic after dark (if they ever had to go up there for any reason, but for the most part, it remained closed).
So after talking a bit under the attic about all this, we headed back down, when all of a sudden the alarm for the church goes off. Their motion alarm, which we disabled on the way back in, was going ape shit, and Martyn ran over to the panel and couldn't seem to disable the alarm. He shouted at us that it was linked to the cops so we should bail while he tried to disable it or stop the police from coming. We left but the security company called and they disabled it remotely and didn't get the cops to come, but it still freaks us out that that happened, and we've always been meaning to go back, just to test our luck.