On July 29, 1927, Metropolitan Sergei Stragorodsky, acting as de facto head of the Russian Orthodox Church, signed a statement of unconditional loyalty to the Soviet State.

In the midst of World War II Stalin decided to allow the Russian Orthodox Church to legally function again after two decades of severe persecution.

Stalin tried to appeal to patriotic feelings of the Russian people especially the peasantry (backbone of the Red Army), many of whom grew up in still deeply religious families.

In 1946 Alexius I presided over the controversial "re-unification" of the Ukrainian Greek Catholic Church with ROC seen by many as a takeover forced by the Stalinist government.

"[3] Pope Pius XII replied: "Who does not know, that Patriarch Alexius I recently elected by the dissident bishops of Russia, openly exalts and preaches defection from the Catholic Church.

According to Christopher Andrew and Vasili Mitrokhin, both Patriarch Alexius and Metropolitan Nicholas "were highly valued by the KGB as agents of influence.

Soviet dissident Aleksandr Solzhenitsyn sharply criticized the treatment of Fathers Gleb and Nikolai in his own open letter to Patriarch Alexius.

Patriarch Alexius died of a myocardial infarction at the age of 92 in 1970 and was buried in the Trinity Lavra of St. Sergius at Sergiyev Posad outside of Moscow.

Supporters praise Alexius I for working hard to ensure the survival of the Christianity in Russia, advocating peace and inter-church unity.

"[11] Metropolitan Eulogius Smirnov, who also was a subdeacon of Alexy I, remembered: "He was a sufferer, who served God in the most turbulent and difficult time for both the Church and the Fatherland.

A leading critic of Patriarch Alexei's leadership was Father Gleb Yakunin who claimed in his books and articles that the postwar hierarchy of the Russian Orthodox Church was controlled by KGB informants.