what does materialism have to do with facts? JUJU is not real. Also the article specifies that they are killing people for materialistic wants, they are trying to cast spells to get money.
People in traditional societies do not think physicality or empiricism is the primary way of determining what is true.
These people are showing you that fear, desperation, and hope lead them to believing a narrative that requires them to take another human being's life in the hope of gaining some physical advantage for themselves. They are literally sacrificing another human being for the hope of improving their own future.
Is what they are doing based on some empirical evidence? No. Are the effects of what they believe still real? Yes. Their hierarchy of ontology has a coherence of its own and allows their society to function, and is a very ancient structure. The concept of the "evil eye" (which is tightly related to these African practices) is a very old mechanism for managing wealth (and good or bad fortune) in communities for thousands of years.
To come along and say "well, this is nonsense. Let's convince them they're wrong by using physical evidence to prove it!" seems pretty hubristic.
Otherwise, no. In this particular case, you'd simply be trying to get people to stop killing innocents in the name of spiritual/religious beliefs; something that is clearly evil and, in my opinion, so is anyone who tries to pretend it is not whether they believe that honestly or is just arguing in bad faith.