There is no fixed line of where, or what countries makeup Europe as it's changed over the years and will probably continue to change in the future.
Well personally i would say Europe has no shared cultural or religious beliefs, it is nothing more than an economic organisation. That's not to say no counties in the EU share cultural, religious, or any other beliefs, it's that those shared similarities are not what define it.
To be fair, people from Ohio and California share a common US identity. Farmers in the US midwest might not share a common cultural identity with, say, people living in the Mayan peninsula. Yet, both are part of the North American continent. However, within the US there are certainly cultural norms and dialectical differences. Ask midwest farmers how they feel about those East Coast liberal elites, or ask the coastal states about all those irrelevant "flyover" states in the middle. It's interesting to me that you desire an integrated Europe where Swedes feel a cultural identity with Portuguese. While I might recognize both as being part of a broader European base, from an American point of view I don't really think of the two as culturally linked. From my point of view the two have very different customs, music, food, etc. Isn't that where most national boundaries ultimately start anyway? Most of my country is the way it is not because the Inuit shared a cultural link with Texans, but because politicians 'bought' huge swathes of land from unsuspecting indigenous people. I feel like you're trying too hard to create a some kind of in-group vs out-group boundary, as if your identity as a European is threatened if some other group is granted access.
An answer to something that even today is a matter of debate amongst many people. The European continent and Europe are (imho) two different things, the former is a geographical grouping, while the latter is an organisational structure.
Don't worry, the way things are going, the Russians will draw a nice solid line for us soon. No influence from our side needed (or regarded) thank you.
It's funny, I hardly even think of the UK as being part of Europe. It doesn't use the Euro and I requires a seperate travel permit. Brits typically don't speak other languages. When I thought of backpacking across Europe after university I never considered visiting England. Now the UK wants to leave the EU to keep other Europeans out.
Hopefully, if there is a referendum, enough people will see sense and vote to keep us in. The potential, indeed likely, economic consequences of leaving the EU would be disastrous.
Screw the economic consequences, I'm more concerned about losing the protection of the EU from our own government, it's the only thing standing in the way of the UK becoming an inverted totalitarian regime.
To be taken with a pinch of salt as the sample is only six countries. Engraved using an ancient artifact
^^^ Poignant... It's a shame the majority of the world's population seems hell bent on destroying itself rather than appreciation of what we have.