as far as the end of the world by a comet impact. I usually don't subscribe to many "outlandish theories" like this, and I am a Christian HOWEVER...
I don't believe my faith prevents my in believing in other factors, such as the POSSIBLITY of aliens, etc. If God is real, than who's to say he didn't create many others.
That being said, this website examines prophecies and predictions from SEVERAL different sources - bible code, bible, kuran, prophets, mediums, seers such as madam shipton and nostradamus, the third revelation of Fatima, and ancient data from civilisations like the Maya. normally, I wouldn't put too much weight into what one of these sources may say but since they ALL predict a mankiller comet impact in 2012 it has definitely raised my eyebrows.
to sum this site up if you don't want to read it, there are two prophecised comet impacts one in 2007 which will devastate India and the global killer in 2012.
http://www.barry.warmkessel.com/barry/2000Paper.htmlone note - if you examine this website this guy has incredible detail and sophisticated astronomical and mathematical material to support his case. any astronomers here?