Donald Trump’s crusading threat to invade Nigeria and save Christians from Islamist terrorists is typical attention-seeking. Surely even he must realise that unilateral US military intervention would invite disaster. And he’s got his facts wrong. The threat of Islamist terrorism is real, but it affects Nigerian Muslims as much, if not more, than Christians. There’s no evidence of genocide, contrary to the alarmist claims of US far-right internet warriors. Trump’s intervention was about politics, not faith.

In speaking out, he was massaging a key domestic constituency, not acting from genuine, God-fearing concern for “our cherished Christians” in a land he’s never visited. Christian nationalist votes helped clinch Trump’s two presidential victories despite the obvious insincerity of his professed beliefs. His support among white evangelical Protestants is much higher than the average – 72% in April, compared with 40% among all US adults. Trump’s histrionics about Nigeria were primarily for their (and his) benefit.

Cynical efforts by political leaders to harness and exploit religious sentiment are as old as human society. Through his conversion, the fourth-century Roman emperor Constantine co-opted the rising power of Christianity. Medieval popes battled European monarchs who presumed to rule by divine right. England’s King Henry VIII, a self-worshipping misogynist like Trump, even invented his own (Anglican) church. Until 1946, Japan’s Shinto emperor counted himself a living god. The House of Saud gained in authority from overseeing Islam’s holiest sites. And given the way he behaves, Iran’s ageing supreme leader must surely have a direct line to Allah.

Today’s generation of secular authoritarian leaders is similarly intent on exercising absolute power. They, too, are eager........

© The Guardian