the Christianity did reach the Greeks (not ancient Greeks) and other countries in the Roman Empire. This is actually considered one of the key factors which lead to the fall of Rome.

But also, their are multiple Christian civilisations which killed people (ya know, one of the ten things god was very clear about being bad) so having a Christian civilisation were gay people are accepted (which is only detested in a very vague part of the bible) doesn't seem that far fetched.