Well as
@hotelbeneathground said, google is your friend here. These militants kidnap Christian Girls to force them to convert to Islam and become essentially slave wives. From Wikipedia about the aftermath of the 2014 kidnappings (a source that is that is readily available via a google search surprisingly):
The overwhelming majority of the kidnapped girls who were Christian were forced to convert to Islam. The girls were forced into marriage with members of Boko Haram, with a reputed bride price of ₦2,000 each ($6/£4).
So I made a logical inference that any white American foolish enough to wander into their midst would either:
A) Be ransomed off for a potential jackpot or
B) The Americans would send some mad death squad to kill them all and save you, as they're wont to do or
C) Drone the ever-living shit out of them which might kill you and not make you a martyr
I think you may have a somewhat racist view of Nigerians. Yes they're (
edit: I mean Boko Haram here not all Nigerians, but I still think OP may have a racist view of Nigerians as a whole) an insane death cult but they're not stupid. Out right murdering an American for being Christian seems like a one way ticket to being carpet bombed by drones. Or being renditioned to Guantanamo Bay to be tortured for the rest of their natural lives. Not a wise game plan. Evangelical Christians are very powerful in the US and they're not very forgiving. They rarely "turn the other cheek" if you get my meaning.
You are too kind, thank you