Today I got a reply. The Christian Party 'is a political party' and therefore the advert is classed as 'electioneering material' (even though there are no elections of any kind imminent) and that means it's 'exempt from our Code'. So there's proof that politicians are allowed to lie in ads but no-one else is.
In my time working in advertising, I've tried to get ads passed that pointed out that films were available on video six months before they were available on satellite. We were not allowed to say this, because even though it was true at the time, it was 'denigratory' to Sky.
Alcohol brands are not allowed in any way to suggest that drinking makes you more socially successful, even though the main reason people drink is because they know it enhances sociability.
But if you're a political party, and you can say what you like, even when you KNOW it's not true ('definitely' implies proof, and even devout Christians believe in faith without requiring proof - it's the whole POINT of the entire religion).
So I'm writing back to the ASA - if I form the 'Alcohol Liberation Party' and register it as a political party, under their code, if I'm governed by the same rules as the Christian Party, surely that means I can create ads that say 'Drink beer and you'll be the funniest, most popular guy in the room and you are GUARANTEED to pull'.
I'll let you know how I get on.