Why does Jeremiah say, "The Lord of hosts is His name" (Jeremiah 51:19)?

The brilliant setting of this verse (Jer. 10-11) should be noticed. Just before, Israel is told not to learn the way of these idolatrous nations. Their wise men, one and all, were senseless and foolish. But the LORD IS THE GOD OF TRUTH; HE IS THE LIVING GOD, THE KING OF ETERNITY. In the following verse creation is ascribed to Him. Idols and false gods must perish before Him. “The portion of Jacob is not like them … the Lord of Hosts is His name” (v. 16). The glory of the God of Israel must yet cover the earth as the waters cover the sea, through our Lord Jesus Christ, who died and rose again to bring this to pass. He will return to Israel and establish the pleasure of the Lord in the earth; and gladness and song shall fill every heart. The peoples, Israel first, and the nations also, shall come under His righteous sway, and be blessed in Him.

And here a new title of God is found, which, in connection with those related and contrasted "kingdoms," which in the Septuagint give such fitting title to the books, claims for the divine not merely supremacy but totality of power. This is "Jehovah of Hosts," or "Jehovah, God of Hosts": where there is no need to speculate whether stars or angels, or even the hosts of Israel, are intended. "The God of Hosts" claims all these for Him. In this title the divine kingdom reveals itself in contrast with all others, which are sustained or confounded as they move in subjection to it or not. Thus the moral of the book is given at the opening of it.

We do not meet with this name until 1 Sam. 1:3. It came in with prophetic testimony, faith laying hold of Jehovah's glory when Israel had corrupted themselves, and were in a weak and low estate. Scripture reveals that there is a mighty heavenly host, and principalities and powers in the unseen world. God is the God of them all, as well as God of all the elements of nature, which have often been used by Him to punish His enemies. "The stars in their courses fought against Sisera." Judges 5:20. We read of 'the God of hosts' only a few times comparatively; it is mostly 'Jehovah of hosts,' and at times 'Jehovah God of hosts,' showing that it is in connection with Israel that God revealed Himself under this name. Jehovah of hosts dwelt between the cherubim. From the beginning of 1 Samuel these titles constantly occur to the end of the O.T. In Ps. 24:10 the Lord Jesus is shown to be "Jehovah of hosts: he is the king of glory:" cf. Eph. 1:20-21; Col. 1:16. The same title occurs in the N.T. as the LORD OF SABAOTH. Rom. 9:29 (in a quotation from Isa. 1:9), and James 5:4.

Each year Elkanah went to Shiloh to sacrifice unto the LORD of Hosts. It is noteworthy that the name of God as "LORD of Hosts" (Jehovah Zebaoth) appears here for the first time in the Bible. (It is found 281 times in the Bible. It is not found in the Pentateuch; it occurs some 80 times in Jeremiah and 50 times in Zechariah.) It is the name of God as the Lord of power, the Lord of all the hosts of heaven and earth. That it is used the first time in the book which reveals the Kingdom is especially appropriate.

This carries the meaning, THE LORD of hosts. It occurs over 300 times in the Old Testament. It is noticeable that it is the one exception, among these different combinations, that finds its place in the New Testament. (See Rom. 9:29; James 5:4). This gives rise to the use of the word, Sabaoth, which is the Greek equivalent of the Hebrew, Tsaba (Host). This combination is largely scattered throughout the Old Testament, Isaiah alone having 60 occurrences of this beautiful title. It carries the thought of mighty irresistible power and resource in the hands of the Lord.

It is noteworthy that in this book God refers to Himself as "the Lord of hosts." We find this title originally in the first book of Samuel, in the time of the judges, when every man did that which was right in his own eyes, much as is the case today. In that difficult time we read of Elkanah and Hannah, who went to Shiloh to worship "the Lord of hosts." The name is used by many of the prophets, particularly in days of weakness and failure. It is good to know that, in spite of man's failure, there is an all-sufficient God, who has unlimited resources at His disposal.

Finally, Hannah had a spiritual insight beyond that of her peers. She addressed God as the Lord ‘of hosts’ (v. 11) — the first time we read of God being called this name. The Lord Jesus (for He is Jehovah of hosts as Psalm 24:10 makes clear) is the Lord of an unseen army of heavenly beings. This name is not reserved for the Lord Jesus when His people are walking rightly and being faithful to Him (that is, for circumstances when we might have thought He would exercise His might for their deliverance or well-being). In fact, it is generally associated in the Old Testament with times of weakness on the part of His people, in particular spiritual weakness (see e.g. the uses of the name in Haggai). Even if His people are unfaithful, the Lord Jesus remains faithful as He cannot deny Himself (2 Tim. 2:13). There is always a great array of power at the Lord’s disposal. Hannah realised that she could take advantage of it.

Again they plead for God's restoring grace (v. 7), using the expression "God of hosts." In verse 3 they had said only, "0 God," emphasizing God's power, but "God of hosts" emphasizes the fact that, while Israel is few in number, God is the God of multitudes, and therefore able to control far greater numbers than those of Israel. But they can be saved only by God's causing His face to shine, that is, through the intervention of His beloved Son.

For the fourth time in this chapter the words are repeated, “Thus says the Lord of hosts” (v. 7). He is emphasizing the absolute truth of what He says. Though the returned remnant of Israel was very small, God was still “the Lord of hosts,” the Commander of multitudes. Though Israel was scattered far from their land, and are still scattered, He will save them just as simply as He saved the remnant from the captivity of the Medes and Persians. He will bring them back eventually to dwell in the midst of Jerusalem, where He will own them as His own people (v. 8). In Hosea 1:9 God speaks of disowning Israel, calling them “not My people” because of their rebellion against Him. But in the future, they will have pleasure in obeying Him.

More than this, and consistent with it, he adds, "So let Thy name be magnified forever", saying, "The Lord of hosts is the God over Israel" (v.26). What God has revealed is that which rightly magnifies the glory of His name, and as "Jehovah of hosts". He is the God over Israel. Though Israel may seem small compared to the great population of other nations, their God is "the Lord of hosts." Then, in connection with the honor due God's name, he again asks that the house of God's servant should be established before the Lord.