The Tsar was the head of the Orthodox Church. The Church reinforced his authority:
Official Church doctrine stated that the Tsar was appointed by God. Any challenge to the Tsar - the 'Little Father' - was said to be an insult to God.
The Church was very influential among the largely peasant population. It made sure this message was conveyed regularly to them. Priests explained to their followers that Russia was God’s land and that he intended for life to be as the peasants found it.
The Church was give financial rewards from the Tsar for this propaganda.
Most of the Russian population was illiterate and had to rely on what they were told by the Church. It was their only source of education and they tended to believe the teachings of the priests.
However, priests were often not respected by peasants, who believed they were increasingly corrupt and hypocritical. The word of the Church became less respected during the rule of Nicholas II.