This is funny but also sad that someone actually thinks like this.
Forget Bill O'Reilly (Tide goes in Tide goes out)
Here you have (paraphrasing a bit) "They believe that through black magic that you are able to send lighting to strike someone. Can you explain that scientifically because it is something that happens?"
Yes I can. Places with ferric (high iron content) or red soil provide the positive charge required by lightning. Thus with the heavy storms that come after heat waves that chances of getting hit by lighting increases. Add in a lack of knowledge in how to protect oneself from lighting and that increases even more. South Africa has annually anywhere between 100-300 deaths a year from lightning with many more presumed unreported due to cultural traditions of quickly burying the dead due to fear of witchcraft. Confirmation bias and confusion of correlation and causation would play heavily in reinforcing the idea of being able to jinx someone to being struck by lightning. Of course they would only remember the hits and never the misses.