I wouldn't necessarily take it as a bad sign, even if it wasn't how Christ was killed. We don't view Christmas as a negative thing just because the date is not right. The symbol has taken on a meaning over time. If it is based on the pagan symbol, then it was really people's recognition of a greater power before they learned about Christianity (if you would like to see it that way). Well, that's what I think anyway. After all, if you take the view that we really don't know what religion is 'right', it's the way we follow our beliefs that's important.