The text is as follows:
כִּי־יֶלֶד יֻלַּד־לָנוּ בֵּן נִתַּן־לָנוּ וַתְּהִי הַמִּשְׂרָה עַל־שִׁכְמו
ֹ וַיִּקְרָא שְׁמוֹ פֶּלֶא יוֹעֵץ אֵל גִּבּוֹר אֲבִיעַד שַׂר־שָׁלוֹם׃
The ESV has “For to us a child is born, to us a son is given; and the government shall be upon his shoulder, and his name shall be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace.” The New World Translation (the Jehovah’s Witnesses’ translation) is little different from this. It translates El gibbor exactly the same way, capital letters and all.
The phrase I wish to look at is the phrase “Mighty God” (El gibbor) There is only one other place in the entire Bible where this phrase is found, and that place is Isaiah 10:21. There, the phrase refers obviously to the Holy One of Israel (vs 20), the LORD (vs 20), which is “Yahweh,” in Hebrew. Therefore, there can be no question about the fact that in chapter 10, verse 21, El gibbor refers to God. However, the Jehovah’s Witnesses will say that in 9:6, though the verse does refer to Jesus, it doesn’t mean “Almighty God,” but “Mighty God.” This is not born up by the exegesis, since the same phrase describes the Father in 10:21 as describes the Son in 9:6. Furthermore, if Isaiah 9:6 refers to Jesus, then Jesus is the Father. That is, He has the same substance as the Father. Therefore, Isaiah 9:6 is a great place for Christians to go to prove to Jehovah’s Witnesses that Jesus is God.