Jesus answered, “It is written: ‘Man does not live on bread alone, but on every word that comes from the mouth of God (Mat 4:4).’”

“Bread” is physical food, and God’s “word” is spiritual food. Since we are spiritual beings, we live not only on physical food, but also on spiritual food. But, is this all that this scripture says, and was it all that Jesus meant? Pay attention to the phrase “every word that comes from the mouth of God.” At this time, Jesus’ ministry was about to begin—the time for the fulfillment of all the scriptures written about him.

Physical food is not only for our growth, but also for the energy to act and do all our work. In the same way, spiritual food is not only for the salvation of our soul, or the spiritual growth of our faith, but also for the spiritual work we do according to the will of God: that is, for the work we do for the fulfillment of his word.

No, the word is very near you; it is in your mouth and in your heart so you may obey (or, can do) it (Deut 30:14).

Thus, God’s word is not just for your spiritual growth. If so, it would be better to say, “it is in your ears,” because we know that faith comes by hearing the word of God. Note that it is “in your mouth”, and “you can do it, ” according to the above scripture.

Do not let this Book of the Law depart from your mouth; meditate (lit. utter) on it day and night, so that you may be careful to do everything written in it. Then you will be prosperous and successful (Josh 1:8).

Here, God was encouraging Joshua not to let the Law (the word) depart from his mouth so that he could do what it said. To do the word of God means to bring it to its fulfillment. More particularly, the fulfillment, for Joshua, meant as follows:

Be strong and courageous, because you will lead these people to inherit the land I swore to their forefathers to give them (v. 6).

This promise for the inheritance of the land had been given in the time of Abraham, and now it was about to be fulfilled through Joshua, and it had to be fulfilled.

It was by the fulfillment of God’s word that we humans were created.

Then God said, "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground (Gen 1:26)."

If our existence came as the fulfillment of God’s word, then the purpose of our existence must be also for the fulfillment of his word—to rule over all the earth. This must be fulfilled. Just as the Promised Land had to be given to the people of Israel through Joshua as the fulfillment of his word, the above scripture must be fulfilled. It was once inhibited because of our sin and disobedience to God, but now through Christ, the right and power to rule over the earth has been restored to us completely: by grace and in Christ, we have become the heir of the world (Rom 4:13-16). And for this purpose, we were chosen to live in obedience to God doing his word according to his will, not doing our own word according to our will.

And the Lord God commanded the man, "You are free to eat from any tree in the garden; but you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die (Gen 2:16-17)."