Hello, My son recently lost marks on an R.E. test because he used Satanism as an example of a religion, To be perfectly honest it matters little to me if Satanism is classed as a cult or a religion or anything else for that matter but I would like to know what it is 'technically' classed as because I do care about my son's education and I'd love to regain him some marks. Thankyou very much for you time.

I don't know what the CoF is.

But yes, we classify Satanism as a religion. And The Church of Satan is a registered religious organisation in the USA.

Can you explain the difference between a religion and a cult?

"Technically classed as" according to whom? First of all, I don't see why the two terms would necessarily be mutually exclusive. More importantly, "cult" is a loaded and strictly derogatory term. No group would ever identify itself as a "cult". This article elaborates:
http://www.religioustolerance.org/cults.htm

Satanism is indeed a religion, since we have our own versions of main components that other religions have (dogma, ceremony, symbolism, conduct/ethics code, a central source of official literature, etc.). Here in the US and in many other countries, it is legally recognized as a religion.

We do not, however, share the characteristics that are stereotypical of "cults". The Church of Satan does NOT demand that members ever even meet each other, does not demand irrelevant sacrifices from one's own personal life (unless it involves illegal activity; we don't condone that), we don't prevent people from leaving if they want to, etc.

Sorry, i think i should add that it is not me who saw it as a cult, this is what my son's R.E teacher said to him.