It's very possible for Christianity to be true without the existence of angels and demons. The central core of Christianity that Jesus is God. If you remove his messengers (the angels), you still have all of the core. Demons are more-or-less moral wildcards, more like chaos creatures and not necessarily evil. There is no text that calls demons "evil." So we cannot conclude that Christianity is false if we take away or deny the existence of angels and demons.

> There has never been any credible evidence for these other-worldly creatures

There have been many alleged sightings through history, so we have to honestly wonder about their existence. Obviously there's no material evidence. It's not like they leave a stripe of slime behind them, or a piece of their robe gets caught on a drawer pull and left behind.

> My take is that Christianity's authenticity depends on angels and demons being real because of the large rolls they play in the gospels.

Christianity could live on just fine without angels and demons. They are not core at all and only play small roles in the Gospels.

> Do most Christians believe in them and do they purport to have some good evidence?

I believe in them. There is no evidence of them at all. I believe in them because the evidence for God and other parts of the Bible is so convincing that I believe in the angels also.

If angels and demons don't exist, would it still be possible for Christianity to be true in the sense of its core theology, or would that be a reason to conclude it must be false? There has never been any credible evidence for these other-worldly creatures, and it seems if they were real we would have ample evidence for them by now, especially with cell phone cameras and social media.

My take is that Christianity's authenticity depends on angels and demons being real because of the large rolls they play in the gospels. Do most Christians believe in them and do they purport to have some good evidence?