"Be a herald of God's goodness, for God rules over you, unworthy though you are; for although your debt to Him is so great, yet He is not seen exacting payment from you, and from the small works you do, He bestows great rewards upon you. Do not call God just, for His justice is not manifest in the things concerning you. And if David calls Him just and upright (cf. Ps. 24:8, 144:17), His Son revealed to us that He is good and kind. 'He is good,' He says, 'to the evil and to the impious' (cf. Luke 6:35). How can you call God just when you come across the Scriptural passage on the wage given to the workers? 'Friend, I do thee no wrong: I will give unto this last even as unto thee. Is thine eye evil because I am good?' (Matt. 20:12-15). How can a man call God just when he comes across the passage on the prodigal son who wasted his wealth with riotous living, how for the compunction alone which he showed, the father ran and fell upon his neck and gave him authority over all his wealth? (Luke 15:11 ff.). None other but His very Son said these things concerning Him, lest we doubt it; and thus He bare witness concerning Him. Where, then, is God's justice, for whilst we are sinners Christ died for us! (cf. Rom. 5:8). But if here He is merciful, we may believe that He will not change." (from Ascetical Homilies of St. Isaac the Syrian, Homily 60)
"Mercy is opposed to justice. Justice is equality of the even scale, for it gives to each as he deserves… Mercy, on the other hand, is a sorrow and pity stirred up by goodness, and it compassionately inclines a man in the direction of all; it does not requite a man who is deserving of evil, and to him who is deserving of good it gives a double portion. If, therefore, it is evident that mercy belongs to the portion of righteousness, then justice belongs to the portion of wickedness. As grass and fire cannot coexist in one place, so justice and mercy cannot abide in one soul... As a grain of sand cannot counterbalance a great quantity of gold, so in comparison God’s use of justice cannot counterbalance His mercy. As a handful of sand thrown into the great sea, so are the sins of the flesh in comparison with the mind of God. And just as a strongly flowing spring is not obscured by a handful of dust, so the mercy of the Creator is not stemmed by the vices of His creatures." (from Ascetical Homilies of St. Isaac the Syrian, Homily 51).
“The Staretz [Silouan] himself always spoke only of the love of God and never of His justice, but I purposely got him to talk about this, and here approximately is what he said: "One cannot say that God is unjust — that there is injustice in Him — but neither can one say that He is just in our sense of the word. St. Isaac of Syria wrote, 'Do not presume to call God just, for what sort of justice is this — we sinned, yet He gave up His only-begotten Son on the cross?’ To which we could add, We sinned, yet God appointed His holy angels to minister unto our salvation. But the angels, filled with love as they are, themselves desire to wait upon us and thereby accept affliction in our service. And the Lord surrendered the animals and the rest of the created world to the law of corruption because it was not proper for them to remain immune when man, for whose sake they were created, through his own sin became a slave to corruption. So, willingly or unwillingly, ‘the whole creation groaneth and travaileth in pain together until now’ (cf. Rom. 8:20-22) in compassion for man. And this is not the law of justice – it is the law of love.” (Saint Silouan the Athonite, by Archimandrite Sofrony, p. 122)