You contradict yourself.
not at all.
You say "fundamentally multi-ethnic and multi-religious society" but then say "society that accepts reality of predominant Christian and Slavic cultural heritage"
Nobody says that modern human civilization gave answer to all open questions. But, that goes for all societies in the world. To function, societies have backbone, spirit, values, dominant culture, etc. To live in organized society, to avoid anarchy, humans pay prices. Why Americans tolerate English language? Canadians? Australians? After all, why entire humanity tolerate English as global language? Simple- interest. See, Intermarium is best what many could get from Baltic to Balkan, Adriatic to Ukraine.
Where does that leave the Tartars,
you mean Tatars? Tartar is sauce
or atheist Czechs?
With rest of us. If they now live in `Judeo-Christian` EU as it is stated in EU proclamation, why wouldn`t they live in `Slavo-Christian` society?
What about the Kosovans (like it or not, they exist)?
Kosovans don`t exist. Exist only Serbs and Albanians of Kosovo. Some others, too. Actually, Albanians call themselves Shquiptars.
Why would that 'Intermarium' be any better for Lithuania than the much broader multi-ethnic and multi-religious EU that they already belong to, with its larger trading bloc, larger defence force and guarantee against Polish domination of their own language?
You should ask that Lithuanians. What they think of `much broader multi-ethnic and multi-religious EU`. As for `larger trading bloc, larger defence force`, forget it. EU would turn to be something else. It would reduce, modify, crumble. It would split on probably three separate conglomerates (one of them being Intermarium). In future, what remain of EU they may name Magna Germania and that would be multi-ethnic and Germano-Christian society.
So, truly, why would Lithuania choose Intermarium over Magna Germania? Maybe they won`t. Who knows. Its interesting question. Same question goes for Estonia and Latvia, too. Today, they are already deeply germanized societies.