Islamic State 'abducts dozens of Christians in Syria' - but it's not about religion...

The BBC http://www.bbc.com/news/world-middle-east-31601451 manage to report that

'... violent attacks by extremist groups like IS, which has forced Christians living in the territory it controls to either convert to Islam, pay a religious levy (jizya) or face death.'

But seem confused as to the motive. Stupidity or deliberate blindness to the obvious?