Isaiah 51:9 – Awake, awake, put on strength, arm of Jehovah; awake, as in the days of old, the generations of ancient times. Isn’t it you who did cut Rahab in pieces, who pierced the monster?
Isaiah 53:1 – Who has believed our message? and to whom has the arm of Jehovah been revealed?
Most translations change the Holy Name to “the Lord”, making it read, “the arm of the Lord.” The American Standard, and some others, read, “the arm of Jehovah” or "arm of Yahweh". The English form "Jehovah" is based on the Masoretic Hebrew text, while the form "Jehovah" is based on a Greek form that is often transliterated as IAUE. The sounds attributed to these four vowels were read back into the Hebrew tetragrammaton of God's Holy Name to produce the Latin form "Yahweh".
The expression, “the arm of Jehovah,” is often thought to be a title of Jesus, and thus many automatically associate this expression with Jesus. Some have endeavored to show that the arm of Jehovah is God's Holy Spirit and that it is also Jesus, and in some vague manner this is supposed to prove the Holy Spirit is Jesus, or that the Holy Spirit as well as Jesus are both persons of the one God, Jehovah.
Indeed, the term can be used of Jesus in the sense that Jesus performs the work of his God. Nevertheless, in neither of these scriptures do we have reason to think that the Messiah being called the “arm” of Jehovah. When used figuratively in the Bible, the word “arm” usually signifies strength, power. In Psalm 10:15, for instance, we read: “Break the arm of the wicked.” It should be apparent that by “arm” it is speaking figuratively of the power of the wicked. In Ezekiel 30:21, Jehovah says: “I have broken the arm of Pharaoh king of Egypt.” By this He means the power of Pharaoh. There are many scriptures in the Bible that show that Jehovah's arm is used in the sense of strength, power, or as his power extended to deliver, etc. -- Exodus 6:6; 15:16; Deuteronomy 4:34; 5:15; 7:19; 11:2; 26:8; 2 Kings 17:36; Psalm 98:1; Isaiah 30:30,32; Jeremiah 48:25, Luke 1:51 and more.
Likewise, Isaiah 51:9 and Isaiah 53:1 are both speaking of the strength, the power of Jehovah. Neither of these scriptures directly apply the term “arm of Jehovah” to Jesus, although in Isaiah 53, Jehovah's arm, His strength and might is certainly exercises through the Messiah, in harmony with Isaiah 11:2,3; 61:1,2; Micah 5:4 and 1 Corinthians 8:6.
Awake, awake, put on strength, arm of Jehovah; awake, as in the days of old, the generations of ancient times. Isn’t it you who did cut Rahab in pieces, who pierced the monster? — Isaiah 51:9, World English Bible
Since Jehovah never sleeps, why would God’s people pray for his arm to “awake”? Matthew Henry’s comments are very applicable here: “He that keeps Israel neither slumbers nor sleeps; but, when we pray that he would awake, we mean that he would make it to appear that he watches over his people and is always awake to do them good. The arm of the Lord is said to awake when the power of God exerts itself with more than ordinary vigour on his people’s behalf. When a hand or arm is benumbed we say, It is asleep; when it is stretched forth for action, It awakes. God needs not to be reminded nor excited by us, but he gives us leave thus to be humbly earnest with him for such appearances of his power as will be for his own praise.”*
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*Henry, Matthew. “Commentary on Isaiah 51”. “Matthew Henry Complete Commentary on the Whole Bible”.
http://www.biblestudytools.com/commentaries/matthew-henry-complete/isaiah/51.html.
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Likewise, the prayer requests the “arm of Jehovah” to “put on strength”. Certainly the idea is not that Jehovah’s arm was weakened so as to have need to be supplied strength from elsewhere; rather, it is an expression of readiness of power to accomplish a task.
The prayer is asking for Jehovah to use his strength to act “as he did in the days of old”, when Israel was delivered from Egypt, represented here as “Rahab”. — Isaiah 30:7.
Who has believed our message? and to whom has the arm of Jehovah been revealed? — Isaiah 53:1.
Who has discerned the arm, the power of Jehovah, and God’s great provision for man’s needs? This prophecy is concerning the message of Christ, for it is through Jesus that the arm, the power, of Jehovah is revealed. How many have truly comprehended the greatness of the length and the breadth and the height and the depth of the love of God expressed in Christ, which passes all understanding? (Ephesians 3:14-19; Philippians 4:7) The message of Jesus, although often presented through the distortions of man's creeds, has been proclaimed here and there for almost two thousand years, and while there have been many who have professed to have believed the message, in reality very few have appreciated the fullness of the message. Look out all over the world today and see how few there are who believe the message of God in respect to his great plan. The great majority are blinded by the adversary, the God of this world, who has blinded the minds of those who do not believe, lest the light of the goodness of God should shine into their hearts. (2 Corinthians 4:4) The apostle’s words imply that the great adversary is the one who is especially interested in beclouding the mind, and that God’s truth is the special thing intended to enlighten the mind, and that not everybody is in condition of mind to be profited by this great light that would shine forth.
The question asked by the prophet implies that only a few would truly believe the message, so that it would bring a genuine appreciation to their mind and heart. When we view the matter in the light of the eighteen centuries, and then think of how little faith there is today in the promises of God, we can well understand God’s standpoint in speaking through the prophet and saying, ‘Who is it that has believed?’ Practically nobody. We indeed see great churches, and sometimes fine buildings, often with large congregations and yet if we would inquire for the faith once delivered to the saints, if we inquire for an intelligent understanding of God’s great plan, how few would you find who have that understanding, who have delivered the message, who have accepted it, and who are upholding the faith once delivered to the saints.
What we do not find in Isaiah 51 or Isaiah 53 is that God is more than one person, or that God's Holy Spirit is a separate and distinct person of Jehovah, or that the Messiah is a person of his God, etc.
