"At this the man's face fell, and he went away sad, for he had many possessions."
This man was perfect. He had it all, wealth, power, youth and an impeccable moral record. Jesus himself, upon examining him closely, loved him. Surely he would make a great disciple! But when the invitation comes straight from Jesus's own mouth, the man goes away sad and all that excitement that was once in his face turned into utter defeat. Eternal life was not worth more than his possessions.
So this man, whom any of us would want in our own churches, fails to become a disciple of Christ. He is the first and only man Mark depicts as not immediately leaving everything behind and following Jesus when he says "Come and follow me." To those whom much has been given much will be demanded.
This is a powerful reminder that a high social status is no ticket into heaven, but rather the ability to be brought low like a child. It is not what you have that counts, but what you are willing to give up. In the end, it is not the "righteous"who end up following Jesus, but the sinners and tax collectors, dirty fisherman and prostitutes, drug addicts and thieves, slanderers, sorcerers, and adulterers for all they have to give up is their past lives so that Christ might give them new ones.