Yes, of course you can.
If we are to be totally honest no-one really
knows anything about the spiritual dimension but plenty of people are absolutely convinced that their particular set of beliefs are the truth. You need to remember that most of these "truths" were hammered into their minds well before they developed the faculty of critical reasoning and they have built the whole fabric of their lives around them. Therefore, any challenge to them is a direct threat to their world and will not be well received.
As for my own personal views, well, I will not rule anything out or in but I have no time for organised religion which I see as little more than groups of (mostly) old men seeking power over others and, indeed, even over Governments. Look at the recent strife in Italy where the Pope had the Italian Government on the run over their decision to allow a hopelessly comatose patient to die. Luckily, she did die before the Government could intervene and force the hospital to keep her alive indefinitely. The Catholic Church also offers women in third world countries like Mexico and the Phillippines the choice between perpetual pregnancy with its attendant poverty or abstinence with a superstitious fear of damnation as the booby prize for the "wrong" choice
If you think that is bad just look at the numbers of holy rollers who have infiltrated parliament, some as members of parties, like Mr Porter (W.A. Attorney General) others, like Mr Fielding (Family First) standing on their beliefs. How many others we don't know about have their thinking clouded by religious influences?
As for ghosts, well, I certainly believe there is another dimension to existence and have had some experiences which suggest the paranormal is definitely real. Like any good scientist I keep my mind open and treat each new piece of information with respect, whether or not it "fits" the puzzle as I understand it. One day I may get an answer but I am not holding my breath and, in the meantime, it is nice to have a few mysteries around - if only to prevent scientists and others from getting too far up themselves.: