First through the senses — by impressions. As a person recognizes and begins to love the beauty of nature in its general features before any learning, by becoming familiar with it through simple contemplation and childhood experiences, so in the Church the first notions of God, the earliest and more important in the person’s life, come through the contemplation of images, actions, symbols pointing to the spiritual world.
The mother, the object of all the love and tenderness of the child, stands with a reverent expression and prays before the Savior’s icon; the child looks at her, then the image — and does not require long explanations of what it means. This is the first, silent lesson of the Knowledge of God.
The child in church: the beauty of the church, the lighting, the bright vestments of the priesthood, the singing and silence of those standing and praying while facing the sanctuary, the holy activities, the lack of everyday objects, the forbidding of irreverent movements, the demand for attention to something higher, special — these are lessons of reverence before God, which cannot be replaced by any fancy speech of a religious teacher.
In these lessons, one cannot notice the moment at which the children begin to understand what is being read or sung in the church; we only know that we loved our Savior long before the lessons in the Law of God, because we often heard readings about Him, prayed to Him often, kissed His Gospel, cried about Him when the Gospel of His Passions were read, and rejoiced with all our hearts, celebrating His Bright Resurrection.
This abundance of blessed influences and the very grace of God is what parents deprive their children of by not taking them to church to receive Holy Communion and not taking them to church from infancy, for the empty reason that the child doesn’t understand anything — as if only an analyzing wisdom is the guide of all influences acting on the development of a person!
Here, especially, is where religious feeling is instilled, the main engine of spiritual life. The loss of this time and this method of developing the heart is a loss that is irreparable. Later, the child will assimilate even abstract notions, and will begin to repeat lessons, but the heart, which is already occupied by other influences and tendencies, will be dull and deaf to spiritual impressions.
—Archbishop Ambrose (Kliucharev)
Version française, ici.