One of the most powerful ways for the elites to counter the spread of any dissenting idea, is to convince people that such ideas and those who support them are somehow socially "dangerous", by accusing them (often with the help of massive amount of logical fallacies) of a series of evils such as: that they corrode the moral fiber of the nation, that they corrupt the minds of younger generations, that they can lead to potentially harmful or unhealthy behaviour, that they could damage the national economy and/or public health and/or the ecosystem, that they promote hate or discrimination, and so on... slowly planting into the people's mind the idea that an "unchecked" spread of dissenting ideas could lead to a catastrophic collapse of civilization itself.
In this way it is possible to create a widespread climate of hate and hostility against dissenters and free-thinkers even without openly insulting or calling for violence or discrimination against them.