"By this shall all men know that you are My disciples, if you love one another." No words can be plainer; & the consequence is equally plain, however hard it may bear upon any professors, that though they could speak with the tongues of angels, had the knowledge of all mysteries, a power of working miracles, & a zeal prompting them to give their bodies to be burned in defence of the truth; yet if they love not the brethren, they are but as sounding brass or tinkling cymbals: they may make a great noise in the church & in the world; they may be wise & able men, as the words are now frequently understood; they may pray or preach with great fluency; but in the sight of God their faith is dead, & their religion is vain.
~John Newton, A Pen Dipped in Love