Martin Luther had many friends and valued them highly. In What Luther Says (Vol. 1; Concordia Publishing House), he reflects on John 15:9.
"Although we are moved to suspicion and displeasure, we should beat these back and remember not to allow them to sever the bond of love and extinguish its fire; but we should cling firmly to our friendship in the face of them. And if perchance displeasure and disagreement arise, we should renew and improve our love and friendship. For to begin to love is not so great, but to remain in love (as Christ here says) is a real task and virtue. In the estate of matrimony many meet who at first are ready to eat each other for great love and passion, but later on they become deadly enemies.
"This also happens among Christian brethren. Probably for an insignificant reason the bond of love is severed, and those who ought to be most firmly knit and bound together are torn apart, so that they turn into the worst and bitterest enemies. ... This is the joy and delight of the devil, who strives for nothing else but to disturb the love among Christians and to arouse pure hatred and envy."
Lecturing on the parting of ways between Abraham and Lot (Genesis 13:5-7), Luther spoke about the spiritual blessings of Christian friendship.
"Throughout life a faithful friend is a very great blessing and a very precious treasure. This is true not only in view of the ordinary dangerous difficulties in which he can offer help and consolation but also in view of spiritual temptations.
"For even though your heart is thoroughly confirmed by the Holy Spirit there is nonetheless a great advantage in having a friend with whom you can talk about religion and from whom you may hear words of comfort."
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