In Orthodoxy the purpose of our lives is to grow in the image of God, achieving with God's active help, a spiritual growth called God-likeness or Theosis. It is a grave error, however, to try to do this by ourselves, without a guide and direction. In the tradition of our Church such a director usually is a bishop, priest or monk. This is the "spiritual father." In Greek we call him "pnevmatikos pateras." In the Slavonic tradition he is called "staretz." If you are serious about your spiritual growth as a Christian, you will seek out and receive the guidance of a spiritual father. St Thallasios the Lybian, in his book, On Love, Self-Control and Life in Accordance wtih the Intellect, put it well: "A wise man is one who accepts advice, especiallyl that of a spiritual father counselling him in accordance with the will of God." ~~~ from Fr Harrakas' book
PS: I'll have more to say later... I'm in a hurry now