Wiki - The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually ceased or destroyed by the intolerant. Karl Popper described it as the seemingly self-contradictory idea that in order to maintain a tolerant society, the society must retain the right to be intolerant of intolerance.
The line is when actions are taken.
Religious people are allowed to believe and say that homosexuality is a sin.
Atheists are allowed to believe and say that religious people are stupid.
I don’t believe that hate speech is defined the same way everywhere, but it’s not really that difficult to say “we don’t legislate sin; nor stupidity.” People expressing their views is not necessarily hate speech. Calling something a sin or calling something stupid is not on par with a call to action, or attempt to intimidate a group of people.