And Jesus answered him, "It is said, 'You shall not tempt the Lord your God.' " And when the devil had ended every temptation, he departed from him until an opportune time. Luke 4:12–13 (RSV)
We err in our thinking about the devil by considering him more powerful than he is or giving him little thought.
The devil wants to be God and cannot. God is God, and no power can undo Him. Thus the devil's longing to be God will never come to pass. Since his efforts against God always fail, he assails us.
We are created in the image of God so we may know and love God freely as He loves us. The devil uses our freedom to tempt us away from the Father. As Adam and Eve reached to unseat God, so we are tested in like manner.
Like Jesus, we resist with the Word of God. We refuse the lie on the lips of the devil for what it is, a lie. He may offer us all things, but he does not even have his existence apart from God.
As he did with Jesus, he will depart, for a time, seeking a moment to lay before us yet another trial. The devil tried Jesus on the cross when the crowds shouted for Jesus to come down from the cross. He tempted Jesus through the words of the thief on the cross next to His, "Are you not the Christ? Save yourself and us!"
Even as His life was fading, Jesus trusted the Father over the schemes of the devil. So might we as well when the opportune time comes for the devil to test us. Like our Lord, we trust only in the Father and His promises.