On the Church:

What does the rite of conversion from different beliefs and confessions and of being united to the Orthodox Church show forth? The indispensability of the rejection of false beliefs and confessions, of the renunciation of errors, of the confession of the true faith, and—of repentance for all former sins and of the promise to God to keep and firmly confess the blameless faith, to guard against sins, and to live in virtue.

St. John of Kronstadt