Liberalism rejects ideological struggle and stands for unprincipled peace, thus giving rise to a decadent, Philistine attitude and bringing about political degeneration in certain units and individuals in the Party and the revolutionary organizations.
Liberalism stems from petty-bourgeois selfishness, it places personal interests first and the interests of the revolution second, and this gives rise to ideological, political and organizational liberalism.
Liberalism is a manifestation of opportunism and conflicts fundamentally with Marxism. It is negative and objectively has the effect of helping the enemy; that is why the enemy welcomes its preservation in our midst. Such being its nature, there should be no place for it in the ranks of the revolution.

https://www.marxists.org/reference/archive/mao/selected-works/volume-2/mswv2_03.htm

Liberalism is the pacifying of the proletariat in class conflict to benefit the bourgeoisie and uphold capitalism.