A liberal simply lacks the IQ to comprehend the subject so believes in Stalin
"Believes"?
Americans BELIEVE. Others -- HAVE OPINIONS!
"Liberals" believe in Stalin?

Only a product of decades of US propaganda could lump together "liberal" and Stalin.
Why do you insist on using the words the meaning of which you do not understand?!
Marxism is a true child of Western civilisation of the 19-20 century a dialectical view of social change (Wiki). From the off it was picked up by different thinkers and applied to the realities of their respective countries. In Russia it was adopted by a militant group of Jews closely connected to their German counterparts and financial clans of US and Britain (Rockefellers and Rothschilds); later this group became known as Bolsheviks.
In Soviet Russia itself, the Marxist revolutionaries were often denounced as a Western implant, dominated by Jews, backed by Western money and manipulated by German intelligence (Norman Davies. Europe a History). Led by Lenin and Trotsky, Bolsheviks took power in two capital cities of the Russian Empire and started a new era in the history of Russia and the world.
And here we come to an interesting question: why, so opposed to commies West comes like a ton of bricks on Stalin, but has nothing negative to say about neither Lenin nor Trotsky? Could it be because
Stalin who followed his own brand of Marxism,
put an end to Westernised ideology of Lenin and Trotsky faction in Russia, and reversed some most damaging effects of their policies, bringing Marxism in line with traditional Russian life-style, Orthodox values and open mind-set?
The fact is --
practically all the ideological paradigm of the modern West implemented by politicians of "Generation '68" and commonly referred to as Liberalism, is a derivative of Marxism, only not in its moderate (Stalins) manifestation, but in its extreme. Calling a spade a spade, --
the West now lives and acts according to the precepts of Trotsky, Gramsci, and the recommendations of Marcuse. The brightest representative of this trend is
Bernard Henri Levy; but he's only a junior student of
Sartre who in his time blessed Pol Pot to "build a just society".
Sick, distorted, pushed to the absurd Trotskist dogma of Marxism is the main current ideological path of the West, where - exactly in line with the precepts of Lev Davidovich Trotsky - a cruel doctrine of complete atomization of human beings and full control of them by society represented by the "selected intellectuals" (Levy) is implemented.
Abolition of gender differences;
the destruction of the authority of a family;
the destruction of a family as a fundamental unit of society;
abolition of traditional cultural values;
reliance of the elites on the newcomers from alien cultures in order to control the indigenous population;
freedom for anti-Christian propaganda and actions;
a ban on freedom of thought (thought crimes);
and dictate of minority agenda groups (political correctness);
denial of majority right;
an all-consuming lie, which is to be accepted as truth without a question because I do not agree with what you have to say, but I'll defend to the death your right to say it gave way to liberal Trotsky paradigm
elite knows best...
And, of course, the "export of revolution" a spite of coloured revolutions and an Arab Spring all in the name of spreading democracy... That is -- the forcible introduction of the "right" ideas in the "wrong" heads by means of the most "humane" in the world -- NATO military machine...