[Jesus' fasting] was not an arbitrary choice of something to do in the face of Satanic temptation. It was a voluntary act of identification with the people of God in their wilderness deprivation and trial. Jesus was saying in effect, “I have been sent to lead the people of God out of the bondage of sin into the Promised Land of salvation. To do this I must be one of them. That is why I was born. That is why I was baptized. Therefore I will take on the testing that they experienced. I will represent them in the wilderness and allow my heart to be probed with fasting to see where my allegiance is and who is my God. And, with the Spirit’s help, I will triumph through this fasting. I will overcome the devil and lead all who trust me into the Promised Land of eternal glory.”
In other words, Jesus’ fasting was not only preparation for testing, it was part of his testing, in the same way that hunger was a test of faith for the people of Israel in the wilderness. Moses said, “[God led you in the wilderness] that He might humble you, testing you, to know what was in your heart, whether you would keep His commandments or not. And He humbled you and let you be hungry” (Deuteronomy 8:2). So it was with Jesus. The Spirit led him in the wilderness and let him be hungry that he might test him to see what was in his heart. Did he love God or did he love bread? But that doesn’t mean that his fasting was not also—even at the same time—a weapon in the fight against Satan. Fasting tests where the heart is. And when it reveals that the heart is with God and not the world, a mighty blow is struck against Satan. For then Satan does not have the foothold he would if our heart were in love with earthly things like bread.