25 And when Jesus saw that he answered discreetly, He said unto him, You are not far from the kingdom of God. What is the meaning of such moderate praise? Believe in one God, and love Him with all your soul, and with all your strength, and with all your heart, and love your neighbour as yourself; if this be the faith which makes man perfect for the Kingdom of God, why is not the Scribe already within, instead of not far from the Kingdom of Heaven? It is in another strain that He grants the Kingdom of Heaven to those who clothe the naked, feed the hungry, give drink to the thirsty, and visit the sick and the prisoner, Come, you blessed of My Father, inherit the kingdom prepared for you from the foundation of the world; or rewards the poor in spirit, Blessed are the poor in spirit: for theirs is the Kingdom of Heaven. Their gain is perfect, their possession complete, their inheritance of the kingdom prepared for them is secured.
But was this young man's confession short of theirs? His ideal of duty raises love of neighbour to the level of love of self; what more did he want to attain to the perfection of good conduct? To be occasionally charitable, and ready to help, is not perfect love; but perfect love has fulfilled the whole duty of charity, when a man leaves no debt to his neighbour unpaid, but gives him as much as he gives himself. But the Scribe was debarred from perfection, because he did not know the mystery which had been accomplished.
He received, indeed, the praise of the Lord for his profession of faith, he heard the reply that he was not far from the kingdom, but he was not put in actual possession of the blessed hope. His course, though ignorant, was favourable; he put the love of God before all things, and charity towards his neighbour on a level with love of self. And when he ranked the love of God even higher than charity towards his neighbour, he broke through the law of burnt offerings and sacrifices; and that was not far from the mystery of the Gospel.
Source: On the Trinity (New Advent)