@Dušan, I’ve never been to Serbia so I can’t cite a reciprocal experience. Maybe one day. I have talked to people from Serbia online and they all seem pretty cool which is refreshing since propaganda claims they’re all haters, lol.  Again, I haven’t been to Serbia but seen plenty of Cro and Bosnia (including Serbs in these countries) as well as Serbian communities in the U.S. and Canada and I’ll say that Croats are more “religious” on average. I say religious loosely because Croats praise their religion more than Serbs even though neither really go to church very often nor to do they impose religious austerity on themselves. That’s definitely true for young people. Older people (like 60+) go to church more than once a week. 
@Dušan, are you sure you weren’t speaking standard Serbian? (Ekavica + some Serb words)? If you were in Slavonia speaking with a Serbian accent then I can see how that’s not exactly welcomed.