John Gill - Exposition
John Gill
By this shall all men know,.... Not only by this you yourselves will know that ye have passed from death to life, that the true work of grace is begun upon your hearts; nor only by this will you know one another to be Christians; but by this all men, even the men of the world will know, that ye are my disciples, if ye have love one to another: and own and acknowledge it, as Tertullian (n) says...