Where the terms "multicultural" and "religiously tolerant" apparently mean something quite a bit different from today (just like Athenian democracy from ours, for example).
I know this is a taboo subject, but we should stop acting as if religion was a racial attribute. It's not. Religions are opinions, and people will have to accept that others will take those opinions into account when it comes to forming a political union.
The difficult thing is that only individuals can hold opinions but only countries can join the EU. So we are forced by the very nature of this decision to make a summary judgement that ignores individual opinions and therefore will be very unfair to some.
This is something I am personally struggling with when it comes to Turkish EU membership.