Understood. Christendom and the faith of Christ are two different things, although there are superficial similarities. In terms of history and tradition, however, the Church of England is significant, and I don't believe the monarch is supposed to be defending Hinduism, even though Charles has said he wants to be "defender of [all] faith[s]."

As for Obama, he may as well have taken his oath on a Koran, although that would not have gone over well.

What the scripture says is that the Church of Christ would be attacked by a growing apostasy, and events like these are certainly signs of it.