1) I doubt either nation considers him a god.. just really proud of his accomplishments... although under a healthy influence of rakija I don't think a discussion with your "host" about pretty much anything would have been reasonable.

2) In Serbia you don't have to feel indebted when someone offers you a drink. I believe this is true for many "old-school" cultures. I realize it might seem intimidating or aggressive but don't fear. Just have a drink ;)

3) Nikola Tesla was Serbian. And yes he was born in Croatia (there are lots of us)... but I have a feeling your host would've been more offended had you replied "Who?". Either way you made it out of there in one piece didn't you?