No, it's not. It's not real the same way God isn't real, ghosts aren't real, and so on.
And it won't stop millions of people in believing it and self-deceiving themselves enough to make other feeble minded ones as infected.
Although in Voodoo's defense, they've got an awesome mythology. That Baron Samedi (aka Baron Saturday) is one awesome dude.
Of course, keep in mind, if you choose to delude yourself with superstitions that, say, some kind of extraplanar entity can make your wishes happen if you ask it hard enough, you're going to associate when it happens and disregard when it doesn't and become a bigger lunatic because that's kind of how your brain works.
Same thing with curses. If you really think having a black cat cross road before you (or whoever the fuck that goes) somehow brings bad luck, then have one unlucky event correlate with said superstition, you're likely to misinterpret simply chance for some kind of curse or bad luck and end up associating it with whatever superstition, only making that connection stronger and making you more insane for anyone not as feeble minded.