How should Christians react to superstitions?

Using the term "Christian" and "should" together in the same sentence takes a very good mediator or a very patient audience. Obviously, the correct answer will come from the canon "Christians" claim to believe... The Bible. The Bible speaks very clearly against fear, magic and sorcery. Superstitions are putting your trust in things other than God and therefore could fit under one of these categories. Luck, superstition and the like argue against God's omnipotence. Trust not in the arm of the flesh, or the salt, or the cat, or the coin, but cling to the Word of the Lord.

(a more accurate answer)- Christianity IS superstition. Belief in any god is, quite simply, the definition of superstition. Belief in contradictory superstitions, i.e, Christianity and Voodoo may pose problems with one or the other. I guess it comes down to picking your superstition and sticking to it, or accepting that they are all equally wrong.