“Henceforth I call you not servants; for the servant knoweth not what his Lord doeth: but I have called you friends; for all things that I have heard of my Father I have made known unto you.”

John XV 15
This is unquestionably a contrast between an enforced and a free religious condition. It is a transfer from a life compelled by fear, through conscience, to a life that is inspired and made spontaneous by love. The strength of the phrase does not come out in that term servant. It is slave in the original. To be sure, the condition represented by the term slave was not at that time marked so sharply by the contrast of its misery with surrounding circumstances, as it is in our own day; nevertheless, it was a condition to be deprecated; and throughout the Scripture it is spoken of both as a misfortune and a disgrace. Our Savior looked upon his disciples as if they had, as Jews, and as worshipers after the manner of their fathers, been tied up in a kind of bondage. He was a member of the Jewish commonwealth, and was of the Jewish church; he had never separated himself from any of its ordinances or observances, but was walking as the fathers walked; and his disciples were bound not only to the Mosaic ritual, but to him as a kind of Rabbi; as a reform teacher, but nevertheless a teacher under the Jewish scheme. And so they were servants — slaves; they were rendering an enforced obedience. But he said to them, "Henceforth I shall not call you my servants — persons obeying me, as it were, from compulsion, from a sense of duty, from the stress of a rigorous conscience; I shall now call you friends." And he gives the reason why. A servant is one who receives orders, and is not admitted to conference. He does not know about his lord's affairs. His lord thinks first about his own affairs, and when he has consummated his plans, he gives his directions; so that all the servant has to do is to obey. But a friend sits in counsel with his friend, and bears a part in that friend's thinking and feeling, and in the determinations to which he comes; and Christ said to his disciples "Ycu come into partnership with me hereafter, and you stand at friends, on a kind of equality with me. There is to be liberty between you and me hereafter."
Christ, then, raised men from religion as a bondage to religion as a freedom. I do not like the word religion; but we have nothing else to take its place. It signifies, in the original, to bind, to tie. Men were bound. They were under obligations, and were tied up by them. Christianity is something more than religion— that is, religion interpreted in its etymological sense, and as it is popularly esteemed. Christianity is religion developed into its last form, and carries men from necessity to voluntariness — from bondage to emancipation. It is a condition of the highest and most normal mental state, and is ordinarily spontaneous and free. This is not an accidental phrase.
The Nature Of Liberty (1873)