I'd like to add that many of the young CP members and fellow-travellers of the CP in the early to mid-30s (until the Show Trial of '38 and the Hitler-Stalin Pact) were worried about what seemed the much bigger elephant in the room, Hitler's well-oiled Reich. Hitler was only one of many, many Fascist organizations and governments operating and ruling in Europe during this time.
As the attitude of the British and French governments were to appease Hitler and ignore the rest of the egregious Fascist aggression in Europe: the formation of strong Fascist parties in virtually every European nation including Britain and France; Hitler leaving the League of Nations and refuting the Versailles Treaty; Italy invading Abyssinia; Metaxas liquidating thousands; Franco over-throwing the elected Spanish government with the material, soldiers, strategists and strategy of Hitler and Mussolini; Hitler liquidating millions of religious, centrist and left Germans; Hitler implementing the Nuremberg laws along with 1000+ laws that terrorized the Jews of Germany, while the United States and European countries continued to make money from Hitler and other Fascist govt.'s while making light of his oft-stated (and broadcast) plans to invade and control Europe, many young anti-Fascist humanists saw the Communist Parties (outside of the Soviet Union) as the only group active and willing to take on Fascism.
In that, they were right. They also had not visited the USSR to see the direction of totalitarian destruction, lies and then, the Terror after Kirov's murder. It was a choice between two until then inconceivable evils. But the early 30s were a much different time than now.