Elder Sophrony Sakharov relates the following story:
I remember a conversation [Staretz Silouan] had with a certain Archimandrite who was engaged in missionary work. This Archimandrite thought highly of the Staretz and many a time went to see him during his visits to the Holy Mountain. The Staretz asked him what sort of sermons he preached to people. The Archimandrite, who was still young and inexperienced, gesticulated with his hands and swayed his whole body, and replied excitedly, "I tell them, 'Your faith is all wrong, perverted. There is nothing right, and if you don't repent, there will be no salvation for you.'"
The Staretz heard him out, then asked, “Tell me, Father Archimandrite, do they believe in the Lord Jesus Christ, that He is the true God?"
"Yes, that they do believe."
"And do they revere the Mother of God?"
"Yes, but they are not taught properly about her."
"And what of the Saints?"
"Yes, they honor them, but since they have fallen away from the Church, what saints can they have?"
"Do they celebrate the Divine Office in their churches? Do they read the Gospels?"
"Yes, they do have churches and services, but if you were to compare their services with ours how cold and lifeless theirs are!"
"Father Archimandrite, people feel in their souls when they are doing the proper thing, believing in Jesus Christ, revering the Mother of God and the Saints, whom they call upon in prayer, so if you condemn their faith they will not listen to you. But if you were to confirm that they were doing well to believe in God and honor the Mother of God and the Saints; that they are right to go to church, and say their prayers at home, read the divine word, and so on; and then gently point out their mistakes and show them what they ought to amend, then they would listen to you, and the Lord would rejoice over them. And this way by God’s mercy we shall all find salvation. God is love, and therefore the preaching of His word must always proceed from love. Then both preacher and listener will profit. But if you do nothing but condemn, the soul of the people will not heed you, and no good will come of it.”
This excerpt was taken from the book Saint Silouan the Athonite by Archimandrite Sophrony Sakharov.