God’s Word: The Means by Which He Works
Because God is omnipotent, He possesses the power to communicate with us in any way that He desires. In Exodus 3, for example, God got Moses’ attention by means of speaking through a burning bush. God opened the mouth of a donkey in Numbers 22:28 in order to express His will to Balaam. Isaiah 6 records Isaiah’s heavenly vision and subsequent call to serve as a prophet of the Lord.
These events and others like them are spectacular manifestations of God’s power, but they do not represent the most important way that God has communicated with mankind. Hebrew 1:1-2 explains that God, after He spoke long ago to the fathers in the prophets in many portions and in many ways, in these last days has spoken to us in His Son, whom He appointed heir of all things, through whom also He made the world. As magnificent and as miraculous as the above Old Testament interactions with the Lord were, they do not compare with the revelation of His Son, who is known as the Word (John 1:1).
Additionally, God has provided mankind with a written Word that we know as the Bible. The written Word is the means by which God communicates with believers today, and the New Testament speaks of the Bible’s importance numerous times. In Isaiah 55:11, the word that will not return void is none other than that which the human biblical authors have recorded in Scripture.
Another important point is that the word that will not return void is God’s word and not the word of humans. In other words, people cannot make their desires a reality merely by applying Isaiah 55:11 to whatever situation they desire. The only word that God guarantees is the word that proceeds from His mouth. Any other word from any other source does not carry this type of authority.
The LORD also indicated that His word will not return “empty.” The reader must understand the meaning of this term to understand exactly what God’s promise entails. As an adverb, “empty” often carries the idea of “not fulfilled” or “unsuccessful.” A helpful example of this usage appears in 2 Samuel 1:22 in the song that David composed to lament the deaths of Jonathan and Saul. The new king depicts his predecessor to the throne as a mighty warrior whose sword did not return empty. The purpose of Saul’s sword was to make war against his enemies, and his weapon fulfilled this purpose.
To say, then, that God’s word does not return to Him empty is a strong declaration of His sovereignty. So certain is this assertion that the Lord employs parallelism in Isaiah 55:11 to make the point that His word is effective:
It (the word) will not return to Me empty, (declaration)
Without accomplishing what I desire, (first parallel statement)
And without succeeding in the matter for which I sent it. (second parallel statement)
Therefore no one, not even Satan himself, can frustrate the purposes of God’s word, which is the means by which He has determined to work. Isaiah 55:11, then, contains a general principle that affirms that God is all-powerful.
God’s Word: The Means by Which He Announces Salvation
Contextually, the declaration of God’s omnipotence in Isaiah 55:11 relates to the concept of salvation. Typically, the word salvation carries two primary definitions in the Old Testament: physical deliverance and spiritual salvation. We must consider both of these meanings in order to determine which one fits the context of Isaiah 55:11.
Throughout Israel’s history, the Lord was responsible for rescuing the nation during troubling times. The deliverance of the sons of Israel from Egypt is the foundation for this concept. In later times, when the Israelites faced seemingly invincible enemies, they would recall God’s miraculous intervention for His people in Egypt and call for Him to work in such a way once more (e.g., Pss. 44, 77, 98). The concept of physical deliverance from hostile opponents became a powerful illustration by which to refer to spiritual salvation. Just as the sons of Israel were slaves in Egypt, humans are slaves to sin. The Israelites could not escape from their bondage, nor can sinners set themselves free from the sin that entangles them. Only God could deliver the people from Egypt and lead them to Canaan, and only Jesus can deliver us from sin and provide us with a heavenly home.
Since both physical and spiritual deliverance figure so heavily in the Old Testament, which is in mind in Isaiah 55:11? Historically speaking, God’s chosen people faced perilous times during Isaiah’s lifetime. They needed assurance that God would not forsake them during their time of trouble, so physical salvation certainly is a factor in Isaiah 55:11 (cf. Isa. 56:1). However, the verse also anticipates the spiritual deliverance not only of Abraham’s descendants, but also all Gentiles who seek the Lord’s mercy (cf. Isa. 56:6, 8). In short, both types of deliverance are present in Isaiah 55:11.
The significance of Isaiah 55:11, therefore, is twofold. First, by means of His unfailing word, God announced that He would deliver Israel from its overbearing oppressors, and this purpose could not be thwarted. Second, He determined to make forgiveness for sin, transgression, and iniquity (cf. Exod. 34:7) available to any person who trusts in Jesus, and no person or force could frustrate or impede His desire to make redemption possible through His Son’s sacrifice.
When one considers all of these factors, a vivid, powerful image appears in Isaiah 55:11. The almighty God has no equal, so His plans never fail. His purposes always find fruition, so He never is forced to resort to a “Plan B.” Because of His omnipotence, believers can find assurance in the fact that the Lord’s will always will be done on earth as it is in Heaven.
This examination of Isaiah 55:11 reveals to us several interesting things. First, it is God’s purpose that will not return empty, not ours. We cannot legitimately use the verse to proclaim that God will cause our desires to become a reality. For this reason, we must learn to pray as Jesus prayed in the Garden of Gethsemane the night before His crucifixion: yet not as I will, but as You will (Matt. 26:39b). We will find that when our will aligns with His will instead of our own yearnings that God will give us the desires of our heart (Ps. 37:4). Second, God is all-powerful and unconquerable. It is easy for us to despair when we see that many nations and people are hostile toward Christ and His gospel. We must remember, though, that nothing happens in the universe without God’s permission, and He is triumphant over Satan, sin, and death. He graciously has provided us with a glimpse of the consummation of Christ’s kingdom in the Book of Revelation, so we have nothing to fear. When we look at things from this perspective, we can echo David’s often quoted words of confidence: The LORD is my light and my salvation; Whom shall I fear? The LORD is the defense of my life; Whom shall I dread? (Ps. 27:1).
Third, Isaiah 55:11 inextricably is tied to the concepts of evangelism and missions. God the Father purposed to send His Son to pay the price for sin, and this sacrifice makes salvation possible not only to Jews, but also to the rest of the earth’s population: For there is no distinction between Jew and Greek; for the same Lord is Lord of all, abounding in riches for all who call on Him (Rom. 10:12). When we share the gospel with others, some will reject this word just as some of the seed in Jesus’ parable fell on unproductive ground and failed to sprout. Isaiah 55:11 does not guarantee us that any one individual with whom we share the gospel will become a Christian. We may, however, state with certainty that many who hear the gospel will respond to it favorably and become followers of Christ because God’s word is powerful. The Lord has purposed to save all who confess their sins and follow the risen Lord Jesus, and His word will succeed in bringing them to Himself!
 Cf. Matt. 21:42; 22:29; 26:54, 56; Mark 12:10, 24; 14:49; Luke 4:21; 24:27, 32, 45; John 2:22; 5:39; 7:38, 42; 10:35; 13:18; 17:12; 19:24, 28, 36-37; John 20:9; Acts 1:16; 2 Pet. 1:20; 3:16.
 R. Laird Harris, Gleason L. Archer, Jr., and Bruce K. Waltke, eds. Theological Wordbook of the Old Testament, vol. 2 ( Chicago: Moody, 1980), 846.