There is a very thorough answer here, What is Ascension? article
And in reply to Joshiepoo3000 (this is not directly aimed at you, but at all religeon as a whole). I am working on an article about this, but mainly:
When we look at the overall universe being 13.7 billion years old, and humanity being no more than maybe a few million years old (think cavemen..) then it is very likely someone else exists out there who is billions of years old, many of them live on the astral because there are less restrictions to having a physical body. When we are finally able to expand our awareness across the universe and look at it in this way, we can see that the 'God' that religions worship today, is very much the same as the early christian belief that the sun/stars revolved around the Earth. Only when we were able to expand our awareness further out into the universe, were we able to understand that in fact, this was false. I see the same thing happening with religion today, we must expand our awareness if we are to evolve, we must realize that we have the ability to alter our reality through the power of thought. We are not at the mercy of some 'thoughtform', we do not have to fear that they will strike us down or torment us for all of eternity if we do something wrong, those who created us merely did so with a purpose in mind, and have left us here to do as we wish. We were in fact created to be 'gods' which is very plainly acknowledged in ancient texts (Greek, Mayan, Sumerian, Egyptian) predating christianity and all the new religions. We save our own souls. There is a process layed out for 'ascension' (achieving godhead) in the temples of egypt and many other ancient texts predating christianity. And no it does not involve handing yourself over to some thoughtform who uses your psychic energy. It involves work, meditation, expansion of conciousness and greater awareness. If you decide to seek the truth and not live in ignorance, I congratulate you, for not everyone makes it to the afterlife.