1 Not sure what you mean with traditional, İ know there are some Protestant groups with more established doctrine and organization like Lutherans but here in Turkey they dont exist or are süper small groups with 1 or 2 communities in all the country and never outside İstanbul or other mega city. İ repeat that İ have nothing against Protestants and İ dont deny there can be good communities on Protestant Churches but İ prefer something more organized and established, where doctrine is written on paper and priest cant come to you and tell you his personal made up views are right and centuries of developed historic documents are wrong. İ can be wrung but it looks like Protestants have nothing in common beside the solas and this is with respect very weak base, see for example the Bible discussion forum of this site its like some internet soap operaProtestant Churches:
If there are protestant churches nearby, you needn't worry about visiting them: they aren't really as factionalized as people claim. All protestant churches that are "traditional" (following the traditional fundamentals of the faith), will all agree on the basic fundamentals of the faith. They will only disagree on smaller issues.
Your Atheist Brother:
You can explain to him that in Christianity, nationality is not a component of our belief system. Nationality is not a relevant issue. The gospel is the same in any country, and the fundamentals of the faith are the same in any country. A church in Bulgaria may do a few things differently, or sing different songs, or hold differently to some "secondary" issues... but in any "traditional" church, the fundamentals, and the gospel, will be the same.
Last Thing - Reality:
Because all churches you visit are run by humans, and humans are fallen creatures, they will all be imperfect. Some churches have better teaching, and better leadership than others... but none are capable of being perfect.
.
2 İ explained this nationality stuff to my brother but he is the way he is, if some institution is not of Turkish origin he will behave like its some anti Turkish recruitment agency, its good that my brother at least is respectful and lets people do what they want despite his general sarcastic atitude see comment above for more info of my brother
3 And yes İ know the perfect Church does not exist but like İ said having developed historic documents in place of something very general like the solas makes difference