Most likely its an automated web-crawler that found a way to exploit the open-nature of your site. (solvable by requiring captchas on submission of anonymous posts)

It could be Atheists wishing to silence someone who gives voice to ID, or it could be another theist group, angered by you giving voice to atheists.

unless someone has another suggestion.

email has a spam folder and that puts spam off to the side where it can be ignored. Can Neil do this?

Not as easy to do with forum threads. They don't use a similar programming paradigm.

The problem with the site is that machines are able to create their own accounts. Since they can create their own accounts, there is no way for the site to decide who is and isn't an appropriate member without a registration process.

I've suggested captcha solving on login as a way to mitigate anonymous forum posts. Or even logging in.

You will no doubt have noticed that we’re being bombarded with spam. I’m currently logging on at frequent intervals, every day deleting at least 50 entries that come from all over the world. What these folk hope to gain by it I really don’t know, but it may be necessary to change the way we do things on the forum. Neil – the technical wizard who administers the site – says that registration might be a deterrent, and he can then “switch off” undesirables. I don’t like the idea, because we’ve always been open to all-comers and I myself am put off by any websites that demand registration. We may have to do it, though – at least temporarily – unless someone has another suggestion.

Captchas on login. Machines CANNOT solve captchas. Humans at least, can solve them some of the time!

unless someone has another suggestion.

email has a spam folder and that puts spam off to the side where it can be ignored. Can Neil do this?