In the Gospel lesson of Matthew 19:16-26, a man asks Jesus, “Good Teacher, what good thing shall I do that I may have eternal life?” Jesus tells him, “… if you want to enter into life, keep the commandments.”
Of course there are 613 commandments in the Torah, so the man seeks further clarification, so he asks Jesus:
Jesus said, “’You shall not murder,’ ‘You shall not commit adultery,’ ‘You shall not steal,’ ‘You shall not bear false witness,’ ’Honor your father and your mother,’ and, ‘You shall love your neighbor as yourself.’“
Jesus names five of the Ten Commandments and then adds another commandment from the Torah that he must love his neighbor as if the neighbor is his own self (Leviticus 19:18). Jesus neither limits God’s commandments to the Ten, nor does he treat this other commandment as any different or less than the Ten.
St. John of Kronstadt comments on keeping the Commandments:
“One definite commandment was given to Adam and Eve, in order that by fulfilling this one commandment – which was, moreover, a very easy one – men might acquire the habit of fulfilling the will of God, the fulfillment of which constitutes the whole well-being of creatures, and might be strengthened in the love of God.
If we turn our attention to the contrary – to the non-fulfillment of the will of the Creator and the fulfillment of our own will, in opposition to the Creator’s – we observe that little by little a man changes for the worse and perverts his own right nature, created after the image and likeness of God, and becomes God’s enemy. So important is the fulfillment of God’s commandments, and so destructive is their non-fulfillment! By giving to the first men His definite commandment not to eat the fruits of the tree of the knowledge of good and evil, the Lord God revealed Himself as the Guide of the newly-created reasonable creatures, of His children by adoption. Whose fault was it that this guidance was rejected, and that man preferred to be governed by his own will? Even until now, notwithstanding all the progress in sciences and arts, notwithstanding all the treasures of human wisdom, neither the man of ancient nor of modern times can educate himself, because he rejected even from the beginning the guidance of God; for, say, who but God should be our guide? And both at present and in the past only those men successfully completed their mental and moral education who trusted in God and lived in accordance with His commandments, or who now live in accordance with the Gospel and the teaching of the Church, submitting themselves to her guidance. This is useful for all modern teachers to remember.
We have many sciences, but the result obtained is small; our youths have much in their heads, whilst in their hearts they have little – very little and often, alas! Even nothing. Life, then does not correspond with education and science. But ‘though I understand all mysteries and all knowledge, and have not charity, it profiteth me nothing.‘ (1 Corinthians XII. 2, 3.).” (My Life in Christ, pp. 150-151)