Third, Turkey doesn't mesh well culturally with the rest of Europe. There are a variety of important differences, but the most prominent reason is that Turkey is far more religious than Europe, and its Muslim. That wouldn't appear to mesh well with Europe. Furthermore, those countries in Europe that are more relgious (like Poland) are Catholic and more intolerant of Islam. Tossing a large Muslim nation in the mix wouldn't be the best way to keep EU stability.
I have a feeling this has a lot to do with it

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