ISIS have struck at the heart of Christianity, by publishing a front page image in their official magazine of a black Islamic State flag flying above the Vatican.

The magazine, called Dabiq, is more a propaganda rag than a serious publication, and its fourth edition calls for an all-out war against the Catholic Church as well as on Christians everywhere.

It's not hard to see what the article in the ISIS magazine is all about, as it is entitled "The Failed Crusade," and talks of conquering Rome and breaking the crosses of Christians.

According to that publication, it is normal under Islamic law for women of infidels to be captured, used for sex, and then sold as slaves in the market to the highest bidder.

The ISIS threat isn't just limited to Christians, Catholics or the Pope though, as the group have said in the past that Jews, other infidels, and even moderate Muslims should be killed under certain circumstances, if they stand against the Islamic State's principles.