Final answer:
The office of the Holy Synod was created by Tsar Peter the Great to replace the Russian Orthodox Patriarch, thereby bringing the church under the control of the state.
Step-by-step explanation:
The office of the Holy Synod in Russia was created to replace the position of the Russian Orthodox Patriarch. The patriarch was the head of the Russian Orthodox Church, but in 1721, Tsar Peter the Great established the Holy Synod to bring the church under state control. The Synod was headed by laymen appointed by the Tsar himself, signaling a significant shift in religious and political power. Instead of having a single patriarch leading the church, the Holy Synod was collectively in charge of ecclesiastical administration, changing the balance between church and state in Russia.