So ghosts of Roman soldiers walking along ancient warpaths are just messing with us? Apparitions of ghostly children which living children can see, and often befriend, are just the spawn of Satan? Your belief in what 'spirits' are is no less far-fetched than mine. In fact, anyone not blindly religious would tend to disagree with you.
My experience with ghosts has not caused me to question what God said was true at all. I have already formed an opinion on that, and a few spirits here and there aren't going to change it. You can relate to this, I'm sure you feel that nobody, or nothing, anwhere will disrupt your staunch belief in God upon High. I'm not 100% sure on what religion you think you belong to, but that doesn't matter.
Science is not the root of all evil, and science tends to disagree with a lot of what you say. As elusive as ghosts are, their activities can be measured, and studied.
Just look here for an example.
Open your mind. Religion is not the answer to everything.