The Messiah would be the "Son of God".
OT Prophecy NT Fulfillment
Isaiah 9:6-7b
"[6] For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace. [7] Of the increase of his government and peace there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the Lord of hosts will perform this."
Luke 1:35
"And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God."

Tanakh - Neviim - Isaiah 9:5-6b

"[5] For a child is born unto us, a son is given unto us; and the government is upon his shoulder; and his name is called Pele-joez-el-gibbor-Abi-ad-sar-shalom; [6] That the government may be increased, and of peace there be no end, upon the throne of David, and upon his kingdom, to establish it, and to uphold it through justice and through righteousness from henceforth even for ever. The zeal of HaShem of hosts doth perform this."

 Hebrew OT - Isaiah 9:5-6b

ומכש-לע הרשמה יהתו ונל-ןתנ ןב ונל-דלי דלי-יכ   [5]
.םולש-רש דעיבא רובג לא ץעוי אלפ ומש ארקיו       

דוד אסכ-לע ץק-ןיא םולשלו הרשמה הברםל   [6]
התעמ הקדצבו טפשמב הדעסלו התא ןיכהל ותכלממ-לעו      
.תאז-השעת תואבצ הוהי תאנק םלוע-דעו      

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