Absolutely! Although I would have thought it was common knowledge. 62% of the Swiss population have German as their main language, 22.7% French, 8% Italian, and 0.5% Romansch. This is an extraordinary level of diversity for a European country, and as other commentators have noted it isn't like there's a lingua franca: a large proportion of Swiss do not speak the languages used by other groups fluently--for example, 85-87% of Swiss don't speak French at all!

This should be quite straightforward evidence regardless of your cultural assumptions, but many people may not be aware of the impact and cultural importance of the Reformation in Europe, which in general meant that nations ended up with a state religion that was either Catholic or Protestant. Switzerland was pretty exceptional and in the 16th Century (which is the important period here) the population was split pretty much 50/50. This religious diversity is pretty important to its history as well as to wider European history.