Of the teachings and proclamations preserved in the Church, some we possess from written teaching, while others we have received in secret from the Tradition of the Apostles; these both have the same validity [ie. authority] for true religion. And no one will deny these points, at least if he is even moderately experienced in Church [matters].
The Church Fathers regard Sacred Tradition as the safe guide in the interpretation of Holy Scripture and absolutely necessary for understanding the truths contained in the Holy Scripture. The Church received many traditions from the Apostles... The constitution of the church services, especially of the Divine Liturgy, the holy Mysteria themselves and the manner of performing them, certain prayers and other institutions of the Church go back to the Sacred Tradition of the Apostles.
They (namely the Apostles) have not handed down everything in writing, but have also delivered many things in unwritten form. The former and the latter are equally trustworthy, and so we also consider the [unwritten] Tradition of the Church to be trustworthy. Is it Tradition? Seek no further.
Sacred Tradition is the very Church; without the Sacred Tradition the Church does not exist. Those who deny the Sacred Tradition deny the Church and the preaching of the Apostles. Before the writing of the Holy Scriptures, that is, of the sacred texts of the Gospels, the Acts and the Epistles of the Apostles, and before they were spread to the churches of the world, the Church was based on Sacred Tradition... The holy texts are in relation to Sacred Tradition what the part is to the whole.
St. John Chrysostom, in considering the misfortune both of parents that neglect the good upbringing of their children and of the children not well brought up, says this, 'Parents that neglect to bring up their children as Christians, are most heinous murderers of children' (Homily 3, 'Against Those that Slander the Monastic Life '). For child-killers separate the body from the soul, but these parents cast them both soul and body info fiery Gehenna. It is impossible to escape from the former death according to natural law, but it would be possible to escape from the latter death were the negligence of the parents not to blame for it. Moreover, once it comes, the Resurrection is able to abolish bodily death, but nothing can overturn spiritual destruction. Therefore, parents, listen to the word of the Lord, 'Bring up your children in the nurture and admonition of the Lord' (Eph. 6:4).