I suppose on an official basis, this may have been true. But considering the centuries of tsarist repression, they may have blamed the church as well. Stalin attended a seminary for a short while, but he got kicked out.
I don't think that they ever really de-Christianized Russia, at least not successfully. Christianity has come back in Russia.
I can tell you an anecdote.
As you know, Mussolini was a staunch atheist and a staunch socialist. Like his father, who named him after Benito Juarez, the Mexican hero of populism. Benito is not an Italian name, indeed.
His first mistress was Angelica Balabanoff, an Italo-Russian woman who did believe in the Russian Revolution, because she and Benito had socialistic ideas, so they were incredibly enthusiastic about what was happening in Russia. But, after going to Russia, and seeing how nihilistic and self-destructive the regime was (it's sufficient to read Doctor Zhivago, I guess: that suffices), she returned to Italy, disappointed. And she surely denounced all that to Mussolini, who was disappointed as well.
In the meantime, Italy was on the verge of a Bolshevik Revolution, because Communists were taking over. Taking over the factories, the agrarian fields, everything.
The King used to appoint really unfit liberals as Prime Ministers. One failure after the other. The king was terrorized by a Bolshevik Revolution happening in Italy.
Mussolini and his fellow moderate socialists decided to ally themselves with the nationalists. Who called themselves
fasci di combattimento. They had created an army which could outnumber the King's army.
In those years, called the
Red Biennium Mussolini became their leader. That's how fascism was born.
The King appointed Mussolini as Prime Minister because he was the only one who could prevent a Bolshevik Revolution from happening.
This truth is taught in every school, in Italy. And that's what the history teachers taught me.
Unfortunately, Americans believe Mussolini was a rightist leader. Which is false.
He has never been a rightist or a elitist leader. He was a socialist born in a very humble family.
This anecdote is very useful to understand that socialists are not as nihilistic and destructive as those who took over in Russia in the twenties.
Fortunately, after Stalin, Soviet Russia became more and more modern.