Well, from a strictly scientific standpoint, there is no sound evidence for ghosts. This is religion, not science. With a little bit of science thrown in for fun, like seasoning some food with salt. But make no mistake, religion, not science.
If you try to only stick to scientifically confirmed ideas, the entire thing falls apart. But you were aware that a very large percentage, perhaps a sound majority of the planet even, prefers faith-based systems to evidence-based systems, yes? Science is a tool that other people employ for their benefit, but to them, the world is a matter of faith.
This is why it amuses me to hybridize the two in ways that people can understand experientially.