My views on each, in order of likelihood.
Aliens - We will almost certainly find life outside of Earth, it may not be intelligent, but we will find it.
Bigfoot - There is very little chance something like this exists and has gone without being found for so long, especially considering the fact that some people are deliberately looking for it.
Ghosts - It's an extreme stretch to have a situation where the dead interact with the living in incorporeal form. I think we may one day develop a technology to do something similar, though.
God - I don't believe such a thing exists, insofar as people imagine it. Even if our universe does have a creator, it's far more likely that we're the result of a particle accelerator experiment than being the creation of a creature invested in our daily actions. Why would something so powerful even care what we do, when we're so insignificant?
You do not have the right to never be offended.
