You have to be mindful of what you say, that is, you mustn't say things you can't prove. You mustn't lie. Or else, you'll be disproved, and announced publicly as a liar. I don't say that you are not free to lie, though, what I say is, in this case, by lying, you accept such consequences. By saying something, you're responsible to its truth.
You're free to insult, but you don't have to. If you do so, people will get offended, and you'll be excluded, ignored, or insulted back at. Again, you're free to insult, but there will be consequences, and by insulting you take the responsibility, and accept being excluded, or insulted at.
And everybody has a right to not be offended, which has to protect them from bullying, demeaning, racism, etc., called the "right to human dignity":
https://en.wikipedia.org/wiki/Dignity
http://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:120...
> Human dignity is inviolable. It must be respected and protected. (Article 1)
> Everyone has the right to respect for his or her physical and mental integrity. (Article 3/1)
> The right to conscientious objection is recognised, in accordance with the national laws governing the exercise of this right. (Article 10/2)
> Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority and regardless of frontiers. (Article 11)
> Any discrimination based on any ground such as sex, race, colour, ethnic or social origin, genetic features, language, religion or belief, political or any other opinion, membership of a national minority, property, birth, disability, age or sexual orientation shall be prohibited. (Article 21/1)
> Within the scope of application of the Treaties and without prejudice to any of their specific provisions, any discrimination on grounds of nationality shall be prohibited. (Article 21/2)
