A renegade Russian Orthodox bishop defied a church order barring him from leading services Sunday and rejected a demand that he repent.

Bishop Diomid's defiance would set the stage for a potential confrontation in the tightly hierarchical Russian Orthodox Church.

Diomid has made waves by assailing the church for its support of government policies and its contacts with other faiths -- essentially saying the deeply conservative institution is too worldly. Following a decision at the Council of Bishops, the church said Saturday that Diomid was barred from serving. It summoned him to Moscow and demanded he "immediately repent."

But Diomid's nephew, Alexander Nesterov, said Diomid held a service Sunday in Chukotka and told parishioners that he would not repent because he does not believe that he is guilty.

Last week, Diomid's supporters rallied in Moscow calling for the resignation of Patriarch Alexy II and clashed with activists of the pro-Kremlin Nashi youth group that condemned the cleric.

Separately President Dmitry Medvedev attended a ceremony at the Christ the Savior Cathedral on Sunday to mark the 1,020th anniversary of the adoption of Orthodox Christianity by the precursor of the Russian state.