I want to make an argument concerning Haiti being predominantly Catholic. That may be true, but syncretism, which is the blending of say, Catholicism with paganism, is almost always a factor with Africans who adopt Christianity. Am I saying that's always the case?, no! but the Haitians (who were former West Africans) come down as French-African-Caribbean mixes (or mullatos) are indeed blending Catholicism with paganism. What does that mean? It means (the sentence speaking for itself) that they recognize a God, they worship and praise him, attend mass or what-not, but they also conduct Voodoo rituals for what would replace power from God with power from Hell. It's happening with Christians today who have adopted New Age teaching, yoga, Buddhism, Hinduism, and some pagan traditions into their lives for "enlightenment". Being 85% Catholic could mean 85% Catholic-pagan mix.
Finally, how do you explain a lot of these magical rituals actually getting results. There must be some logic behind them or they wouldn't get results regardless of whether it's chance or not because 9 times out of 10, they get results whether you think it's a spirit or not.