Belligerentyouth reminded us that "Nationalism (and patriotism) is an infantile sickness. It is the measles of the human race." Einstein

Thank you for that - that is one of my favourite quotes of all time, expressing as it does an opinion very dear to me. I noticed that you inserted patriotism in parentheses. If you want a quote along similar lines that specifically mentions patriotism, try this one:
"Patriotism is your conviction that this country is superior
to all others because you were born in it." ~ George Bernard Shaw