+ St. Ambrose of Optina, quoted from Living Without Hypocrisy: Spiritual Counsels of the Holy Elders of Optina
In vain do some of the Orthodox marvel at the current propaganda of the Roman Church, at the feigned selflessness and activity of her missionaries and at the zeal of the Latin sisters of mercy, and incorrectly ascribe to the Latin Church such importance, as if by her apostasy from the Orthodox Church, the latter remained longer such, and has the necessity to seek unification with the former. On rigorous examination, this opinion proves to be false; and the energetic Latin activity not only does not evoke surprise, but, on the contrary, arouses deep sorrow in the hearts of right-thinking people, who understand the truth.
The Eastern Orthodox Church, from apostolic times until now, observes unchanged and unblemished by innovations both the Gospel and Apostolic teachings, as well as the Tradition of the Holy Fathers and resolutions of the Ecumenical Councils, at which God-bearing men, having gathered from throughout the entire world, in a conciliar manner composed the divine Symbol of the Orthodox Faith [the Creed], and having proclaimed it aloud to the whole universe, in all respects perfect and complete, forbade on pain of terrible punishments any addition to it, any abridging, alteration, or rearrangement of even one iota of it. The Roman Church departed long ago into heresy and innovation. As far back as Basil the Great, certain bishops of Rome were condemned by him in his letter to Eusebius of Samosata, ‘They do not know and do not wish to know the truth; they argue with those who proclaim the truth to them, and assert their heresy.’
— St. Ambrose of Optina, “A Reply to One Well Disposed Towards the Latin Church: Regarding the unjust glory of the papists in the imaginary dignity of their Church”
“One ascetic woman was besieged for a long time with unclean thoughts. When the Lord came and cast them away from her, she called to Him: ‘Where were you before now, O my sweet Jesus?’ The Lord answered: ‘I was in your heart.’ She said then: ‘How could that be? For my heart was full of unclean thoughts.’ The Lord said to her: ‘Know that I was in your heart, for you were not disposed to the unclean thoughts, but strove rather to be free of them; and when you were not able to be free, you struggled and grieved. By this you prepared a place for Me in your heart.'”
+ St. Ambrose of Optina