The Christian needs another Christian who speaks God's Word to him. He needs him again and again when he becomes uncertain and discouraged, for by himself he cannot help himself without belying the truth. He needs his brother man as a bearer and proclaimer of the divine word of salvation. He needs his brother solely because of Jesus Christ. The Christ in his own heart is weaker than the Christ in the word of his brother, his own heart is uncertain, his brother's is sure.
Taken from the book Life Together by Dietrich Bonhoeffer 1939