If a person wants to get an idea about the pyramids of Egypt, he must either trust those who have been in immediate proximity to the pyramids, or he must get next to them himself. There is no third option. In the same way a person can get an impression of God: He must either trust those who have stood and stand in immediate proximity to God, or he must take pains to come into such proximity himself.
(St. Nicholas of Serbia, Thoughts on Good and Evil)

As it is impossible to verbally describe the sweetness of honey to one who has never tasted honey, so the goodness of God cannot be clearly communicated by way of teaching if we ourselves are not able to penetrate into the goodness of the Lord by our own experience.
(St. Basil the Great, Conversations on the Psalms, 29)

Every one of the poorest men can be humbled and come to know God. It need neither money nor reputation to come to know God, but only humility.
(St. Silouan the Athonite, Writings, I.11,21)

No matter how much we may study, it is not possible to come to know God unless we live according to His commandments, for God is not know by science, but by the Holy Spirit. Many philosophers and learned men came to the belief that God exists, but they did not know God. It is one thing to belief that God exists and another to know Him. If someone has come to know God by the Holy Spirit, his soul will burn with love for God day and night, and his soul cannot be bound to any earthly thing.
(St. Silouan the Athonite, Writings, VIII.3)