When the Lutheran theologians of Tubingen wrote to Patriarch Jeremias II of Constantinople in the 16th century, the Patriarch rejected the Protestant theory of justification. His response is certainly representative of Eastern theology. For instance, at the 1672 Pan-Orthodox Synod of Jerusalem, it was defined:
We believe no one to be saved without faith. And by faith we mean the right notion that is in us concerning God and divine things, which, working by love, that is to say, by [observing] the Divine commandments, justifieth us with Christ; and without this [faith] it is impossible to please God. [. . .]We believe a man to be not simply justified through faith alone, but through faith which worketh through love, that is to say, through faith and works. But [the notion] that faith fulfilling the function of a hand layeth hold on the righteousness which is in Christ, and applieth it unto us for salvation, we know to be far from all Orthodoxy. For faith so understood would be possible in all, and so none could miss salvation, which is obviously false. But on the contrary, we rather believe that it is not the correlative of faith, but the faith which is in us, justifieth through works, with Christ. But we regard works not as witnesses certifying our calling, but as being fruits in themselves, through which faith becometh efficacious, and as in themselves meriting, through the Divine promises {cf. 2 Corinthians 5:10} that each of the Faithful may receive what is done through his own body, whether it be good or bad, forsooth.
The Eastern Fathers speak similarly of the merits of good works. For instance:
"Ver. 6, 7. 'Who will render to every man according to his deeds, to them who by patient continuance in well doing,' etc. Since he had become awestriking and harsh by discoursing of the judgment and of the punishment that shall be, he does not forthwith, as one might expect, enter upon the vengeance, but turns his discourse to what was sweeter, to the recompense of good actions, saving as follows, Ver. 7. 'To them who by patient continuance in well doing seek for glory and honor and immortality, eternal life.' Here also he awakens those who had drawn back during the trials, and shows that it is not right to trust in faith only. For it is deeds also into which that tribunal will enquire." (St. John Chrysostom, Homily 5 on the Letter to the Romans)
"If I be now summoned to depart this life, may I see you in the radiant glory of the saints, together with all them who are accounted worthy through patience and showing forth of good works, with crowns upon your heads." (St. Basil of Caesarea, Letter 222, to the People of Chalcis) "I exhort you to be mindful of the faith of the Fathers, and not to be shaken by those who in your retirement would try to wrest you from it. For you know that unless illumined by faith in God, strictness of life availeth nothing; nor will a right confession of faith, if void of good works, be able to present you before the Lord." (St. Basil of Caesarea, Letter 295, To Monks)
"Hence meditation on the law is necessary, my beloved, and uninterrupted converse with virtue, 'that the saint may lack nothing, but be perfect to every good works.' For by these things is the promise of eternal life, as Paul wrote to Timothy, calling constant meditation exercise, and saying, 'Exercise thyself unto godliness; for bodily exercise profiteth little; but godliness is profitable for all things, since it has the promise of the present life, and of that which is eternal.'" (St. Athanasius of Alexandria, Festal Letter 11 (339 AD), no. 7)
"After our forefather's transgression in paradise through the tree, we suffered the death of our soul - which is the separation of the soul from God - prior to our bodily death; yet although we cast away our divine likeness, we did not lose our divine image. Thus when the soul renounces its attachment to inferior things and cleaves through love to God and submits itself to Him through acts and modes of virtue, it is illuminated and made beautiful by God and is raised to a higher level, obeying His counsels and exhortations; and by these means it regains the truly eternal life. Through this life it makes the body conjoined to it immortal, so that in due time the body attains the promised resurrection and participates in eternal glory."