That very word which I spoke

Then Jesus cried out, "When a man believes in me, he does not believe in me only, but in the one who sent me. When he looks at me, he sees the one who sent me. I have come into the world as a light, so that no one who believes in me should stay in darkness. As for the person who hears my words but does not keep them, I do not judge him. For I did not come to judge the world, but to save it. There is a judge for the one who rejects me and does not accept my words; that very word which I spoke will condemn him at the last day. For I did not speak of my own accord, but the Father who sent me commanded me what to say and how to say it. I know that his command leads to eternal life. So whatever I say is just what the Father has told me to say."

John 12:44-50 NIV

God is truth and light. God’s judgment is nothing else than our coming into contact with truth and light. In the day of the Great Judgment all men will appear naked before this penetrating light of truth. The ‘books’ will be opened. What are these ‘books’? They are our hearts. Our hearts will be opened by the penetrating light of God, and what is in these hearts will be revealed. If in those hearts there is love for God, those hearts will rejoice in seeing God’s light. If, on the contrary, there is hatred for God in those hearts, these men will suffer by receiving on their opened hearts this penetrating light of truth which they detested all their life.

So that which will differentiate between one man and another will not be a decision of God, a reward or a punishment from Him, but that which was in each one’s heart; what was there during all our life will be revealed in the Day of Judgment. If there is a reward and a punishment in this revelation – and there really is – it does not come from God but from the love or hate which reigns in our heart. Love has bliss in it, hatred has despair, bitterness, grief, affliction, wickedness, agitation, confusion, darkness, and all the other interior conditions which compose hell (cf. 1 Corinthians 4:6).

In the future life the Christian is not examined if he has renounced the whole world for Christ’s love, or if he has distributed his riches to the poor or if he fasted or kept vigil or prayed, or if he wept and lamented for his sins, or if he has done any other good in this life, but he is examined attentively if he has any similitude with Christ, as a son does with his father.

St. Symeon the New Theologian
The quote of Saint Symeon is from Fr Milovan's excellent blog, Again and Again.