Today, my teacher said that socialism is still far from being well applied and even the USSR wasn't truly a socialist country. I regret that I didn't ask him so I decided to post it on Reddit to get enlightened about this subject.
I love this question, and if you’re really interested in it, read Trotsky’s Lenin. The man’s life is basically a novel in its own right, and you could not ask for a source closer to the Russian revolution.
Firstly, this is more a political theory question than one of historical fact, but I will attempt to answer it by way of an overview of the inception and early organization of the Soviet state, compared to the commonly held ideas of what a socialist state looks like. It should be kept in mind that there is a realm in Left political ideology with no small number of adherents, who basically define their concepts of socialism in likeness to the USSR and other 20th century Marxist movements. For those people, your question is tautological.
There is not a universally agreed-upon definition of socialism or a socialist state, so whether or not the USSR adhered to the definition of socialism depends on which definition you use. This has been a problem since the very beginning for Marxism, and the man himself was known to lambast self-described Marxists as flippant opportunists and blood-thirsty but low level aristocrats simply resentful of other aristocrats who outranked then (most famously, his son-in-law, attested by Engels to a journalist, which is the source of the famous line, “what is certain is that I myself am not a Marxist”). This “principle-agent problem” response is a common academic answer to the question of whether the USSR was a socialist state or not. However, I’m not generally a fan of that line of reasoning, because it seems to submit that, since we cannot be completely certain on the matter, then we can have no certainty at all. I think historical evidence allows one to make a determination of where the USSR fell on a spectrum of socialist characteristics, without needing to dodge the question entirely since it cannot be answered in a binary yes/no fashion.
In the context of Bolshevik rule, the USSR was clearly not a socialist state in the more commonly held definitions of that phrase. This held true even for notable Marxists of the day, who considered Lenin and the Bolsheviks to be a militant, vanguardist, right-wing offshoot.
Economically, though it had something of a centrally planned economy, there still existed the private exchange of goods and services throughout all Soviet states, so the USSR does not fulfill the idea of a post-private ownership state.
Politically, for most people with some idea of socialist theory, a socialist state is inherently tied to democratic process. The Soviet government though, through all of its evolutions, fails this test spectacularly.
Without general elections, without freedom of the press, freedom of speech, freedom of assembly, without the free battle of opinions, life in every public institution withers away, becomes a caricature of itself, and bureaucracy rises as the only deciding factor.
Other than the span of a few months, from the election of a Constituent Assembly dominated (40.4% majority) by the Bolshevik-opposing Socialist Revolutionary Party (SRs) in November of 1917, to the rapid dissolution of the Assembly by Lenin in January of the next year, the Soviet Union was ruled in a dictatorial fashion by a number of central bodies. From 1918 to 1937, this was the Congress of Soviets and the VTSIK, after which the Supreme Soviet was enacted as the ruling body of the Russian SFSR (later the Russian Federation), and was so until 1990. At no point did the average Russian citizen have any say whatsoever in the laws and policies that ruled their state.
[The deputies of the assembly] brought candles with them in case the Bolcheviki cut off the electric light and a vast number of sandwiches in case their food be taken from them. Thus democracy entered upon the struggle with dictatorship heavily armed with sandwiches and candles. The people did not give a thought to supporting those who considered themselves their elect and who in reality were only shadows of a period of the revolution that was already passed.
There is a flickering of democratic resistance against the Bolsheviks from 1918 to around 1920, but by 1922 all of Lenin’s opponents were either executed, exiled, or had given up fighting. There were indeed still “Soviet councils”, in the contemporary usage of the word soviet, but their function was to implement policy autocratically drafted in Moscow, again first under the Congress of Soviets and then, after 1937, under the Supreme Soviet.
So, as a “citizen worker” of the USSR, you have no say in the utilization or management of the “publicly owned” land and resources you have to work with (as the Bolsheviks brutally quashed the final Trade Union dispute in 1920), you have no say in the laws that govern you, you have effectively no hope of anything approaching due process, and you also cannot emigrate legally (contemporary Marxist theory generally required a borderless state). It does not seem apparent that any of these fundamental realities of the Soviet Union line up with what academic Marxists thought a socialist state would look like. Marx himself almost assuredly wouldn’t have considered the USSR a socialist state. This is without even saying anything of those realities themselves. In our modern value systems, they are dramatically in contempt and opposition of basic human rights, and the core concept of socialist theory is that the socialist state is most favorable to the rights of common people. It is contradictory at its very core to desecrate the rights of the people in order to purse, ostensibly for them, a society better able to defend those same rights.
Here’s Noam Chomsky answering this very question in a more succinct fashion, focusing on Lenin’s dissolution of the actual methods of worker’s control in the “worker-controlled” Soviet state.