Are there any specific arguments you can make that would make the possibility of an afterlife highly likely? For example, what about arguments for the soul, the resurrection of Jesus, or whatever? I keep running into people who say that when we die, we’re just dead. How would you respond to this? If we really die, and there’s nothing beyond our grave, then what would be the point of defending Christianity? What about findings from Neuroscience? What about philosophical arguments for the afterlife? Is there any strong, cumulative arguments that would make highly probable? What about near-death experiences? I’ve been told that those aren’t proof of anything, and that they are pseudoscience and not proof of anything.
The simple answer, at least from my perspective, is no, there is no rational way to "prove" the existence of an afterlife, at least not using any kind of physical evidence today or even by analogy to things we can observe today. I do not trust anecdotal evidence of near-death experiences to be reliable, even if it is mildly suggestive of the possibility of an afterlife. Personally, I would not use this as evidence in a public arena because it is so unreliable that it would detract from any other more reasonable arguments. I have also heard it argued that if virtually all humans believe in some sort of continued existence after physical death, this is evidence that it is more likely true than not true. I do not find this argument to be a valid one.
We can argue from a rational/philosophical view that the afterlife cannot be eliminated as a possibility, but the best I know, there is no reliable, solid "proof" available to us today that there is life after death. This logic opens up the possibility, but does not logically compel one to believe in an afterlife.
I believe that Neuroscience is not particularly helpful either way. Determinists like to create the impression that neuroscience "proves" there is no soul, but such proof is not at all scientific. We can make more or less valid philosophical arguments for dualism–that human consciousness exists apart from any particular physical reality. In other words, we can argue that "I" exist apart from my body. This can lead to the conclusion that it is reasonable to believe, therefore, that a soul does indeed exist. However, such an argument is not particularly compelling. I believe that, at best, neuroscience leaves "room for the soul" (to quote my friend John Beggs).
My belief in a future resurrection is nearly entirely indirect. It is proof by association. It is based almost entirely on faith in the authority of scripture. The same Jesus who raised the dead, healed the sick, calmed the storm and lived a sinless life said that he would come back to judge the world and to raise the dead. Jesus said "I am the resurrection and the life," after which he raised Lazarus from the dead. Evidence for the authority of Jesus and therefore the implication that as an inspired person, his statements about the resurrection are true is indirect, but I believe it is rather strong.
Daniel prophesied the rise of Cyrus, the fact that the eleventh emperor of Rome would persecute the church, the persecutiosn of Antiochus Epiphanes, the date Jesus came to Jerusalem, the fact that Domitian was going to change the Roman calendar and even the duration of the "abomination of desolation" with a mind-boggling accuracy. (See Daniel, Prophet to the Nations, www.ipibooks.com) Therefore, with this evidence for Daniel as an inspired prophet and based on the authority which comes from this, I reasonably conclude that Daniel’s prediction of a future resurrection in Daniel 12 is equally trustworthy. This is not "scientific" evidence of life after death. It is indirect evidence, but to me it is nevertheless strong evidence.
Therefore, the strongest "evidence" but one (see below) that there is an afterlife is that the Bible has unmistakeable and clear evidence for a general inspiration. Therefore, on the authority of these inspired texts, I believe in an afterlife.
Having said all that, I am holding out on you. I reserved the strongest evidence we have available to us that life continues after physical death: that when we die, we are not like Rover, dead all over. The strongest evidence for the existence and persistence of the human soul/spirit is the bodily resurrection of Jesus Christ from the dead (and the associated evidence for the resurrection of Lazarus and others).
I will not go into the details here. I have presented much evidence for the resurrection of Jesus from the dead, including my book Reasons for Belief and a power point at the web site. Let me assume for the sake of argument (a very big assumption!!!) that it has been proven that Jesus Christ did indeed raise from the dead on the third day. This fact would cerntainly imply that physical death is NOT the final end of human existence. That seems to be the point of Paul, as recorded by Luke in Acts 17. God gave proof of the resurrection and final judgement by raising Jesus from the dead. Peter (1 Peter 1) makes a similar point. The resurrection of Jesus gives us a "living hope."
Now, obviously, granting as fact that Jesus Christ did indeed raise from the dead is a very big thing. However I believe the case for the bodily resurrection of Jesus is very strong, even if I will not present it here for lack of space/time. If this is true, then the question of life after death seems to be solved. It is for this reason that I have faith (notice that word faith) that I, too, will rise from the dead.