Christians claim that Isaiah (9:5-6) is telling that Jesus was God, Everlasting Father, Prince of Peace

Isaiah 9:6 is a lie, because in Jewish Bible, Isaiah 9:5 is speaking about the child which has been born during the  time of Isaiah, it is not talking about the future child as Christians claimed in the Christian Bible.

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Hezekiah is called "the mighty God" because this name is a sign that foretells God's defense of Jerusalem through the miraculous sudden mass death of Sennacherib's army.

Therefore thus says the Lord concerning the king of Assyria: He shall not come to this city, nor shoot an arrow there, neither shall he come before it with shield, nor cast a mound against it. By the way that he came, by the same shall he return, and he shall not come to this city, says the Lord. For I will defend this city to save it, for My own sake, and for My servant David's sake. (Isaiah 37:33-35)

Hezekiah is called "the everlasting Father" because this name is a sign, which foretells that God will add years to his life. "Go, and say to Hezekiah: Thus says the Lord, the God of David your father: I have heard your prayer, I have seen your tears; behold, I will add to your days fifteen years" (Isaiah 38:5). Hezekiah is called "the ruler of peace" because this name is a sign, which foretells that God would be merciful to him. Punishment for lack of faith in the Almighty will be deferred and peace granted during the last years of his rule. "Then said Hezekiah to Isaiah: 'Good is the word of the Lord which you have spoken.' He said moreover: 'If but there shall be peace and security in my days'" (Isaiah 39:8). The fulfillment of the above-stated declarations is foretold in Isaiah 9:6, when, after the Assyrian defeat, Hezekiah's glory increased and peace reigned for the rest of his life (2 Chronicles 32:23).