Simply because the Son of God is called the “mighty God” here in Isaiah 9:6 does not entail that He is Jehovah. For JWs, the “mighty God” is not the “Almighty God” (cf. Aid to Bible Understanding [Watchtower Bible and Tract Society, 1971], 919).
Isaiah 1:24 has already declared that “the Mighty One of Israel” is none other than Jehovah (“LORD”). Isaiah 10:20-22 says that Jehovah is the “mighty God.” Deuteronomy 7:21 calls Jehovah “mighty God.” Jeremiah 32:18 also says, “The Great, The Mighty God, The LORD of hosts, is his name.” Thus, the Bible knows no distinction between the mighty God and the Almighty God. Therefore, using the law of transitivity (if a=b, and b=c, then a=c), the Son of God is the Almighty God.
R. M. Sivulka
President, Courageous Christians United