Metropolitan John of PergamosOn Personhood and Dogmatics

"This personal relationship of Christ and the Father is given in Christ to us, so we are enabled to recognise God because we are made sons, who can address God as Father.  In teaching them to pray 'Our Father' Christ gave this privilege to his disciples, and we are brought within this relationship so we can also address God as Father.  There is no one but the Son who ca n eternally address God as Father, therefore only the Son can bring us in to relationship with him self, so we become sons of the Father and thereby able to know God as he is, as God the Father.  The Christian approach to God as Father originates exclusively from this relationship of the Son to the Father, and the right that the Son bestows on us to address God as Father with him.  

"The concept of the paternity of God was common in the ancient world.  To the Greeks, Zeus was ‘the father of gods and men.’  But in the Bible only the Son has the right to address God as Father.  Christ alone is able to reveal that the Father is the identity of God.  Knowledge of God means the acknowledgement that God is the Father.  This relationship that God has eternally with his Son is the relationship that is passed on to us.  We do not therefore come to know God by compiling a dossier of his characteristics, in the way that some dogmatics systems do.  That God is Father is the whole truth of God, so a true understanding of God is only possible with in the identity of the Son of God.  If we a re familiar with Christian doctrine, we may even give this our intellectual assent.  But really to know this is to recognise and acknowledge God as Father, which is the prerogative of the  Son.  A son knows his own father in quite a different way than he knows any one else’s father.  Personal knowledge exists only within relationships that are unique and irreplaceable."

Metropolitan John (Zizioulas), Lectures in Christian Dogmatics