“Then Jesus beholding him loved him, and said unto him, One thing thou lackest: go thy way, sell whatsoever thou hast, and give to the poor, and thou shalt have treasure in heaven: and come, take up the cross, and follow me.”
Jesus looked at him and loved him. One thing you lack, he said. Go, sell everything you have and give to the poor, and you will have treasure in heaven. Then come, follow me — the love is the chapter's most important word: Jesus looked at him and loved him. The command is not a rejection but an invitation spoken in love. One thing you lack: not many things, not a comprehensive failure, but one specific thing. Sell everything: the specific form of the kingdom call for this specific man, whose wealth is the competing loyalty that prevents the unconditional following that discipleship requires.
Church Fathers on Mark 10:21
A certain man had heard from the Lord that only they who are willing to be like little children are worthy to enter into the kingdom of heaven, and therefore he desires to have explained to him, not in parables, but openly, by the merits of what works a man may attain everlasting life.
I wonder at this young man, who when all others come to Christ to be healed of their infirmities, begs of Him the possession of everlasting life, notwithstanding his love of money, the malignant passion which afterwards caused his sorrow.
For in that He loved, or kissed him [ed. note: osculaius, interpretation in Ed. Ben. (?)], He appears to affirm the truth of his profession, in saying that he had fulfilled all those things; for on applying His mind to him, He saw that the man answered with a good conscience.