“...they were to be distinguished by tender and constant attachment to each other.
This was to surmount all distinction of country, of color, of rank, of office, of sect. Here they were to feel that they were on a level, that they had common wants, were redeemed by the same sacred blood, and were going to the same heaven. They were to befriend each other in trials; be careful of each other’s feelings and reputation; deny themselves to promote each other’s welfare. So in 1Jo_3:16 it is said that “we ought also to lay down our lives for the brethren.” This was a new expression of love; and it showed the strength of attachment which we ought to have for Christians, and how ready we should be to endure hardships, to encounter dangers, and to practice self-denial, to benefit those for whom the Son of God laid down his life.”
Alfred Barnes – Notes on the New Testament