Isaiah 9:6 indeed is a prophecy about the "Son," our Lord Jesus Christ. However, as you will see later, Jesus Christ is not the Mighty God referred to nor does this prophecy indicate His alleged divinity.
Isaiah 9:6 reads, "For unto us a Child is born. Unto us a Son is given; And the government will be upon His shoulder. And His name will be Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace." (New King James Version).
Since Isaiah 9:6 was originally written in Hebrews, it would be of help to consult the Jewish Publication Society of America for instance how it renders the verse:
"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." (The Holy Scripture According to the Masoteric Text, 1917 edition).
The Hebrew name Pele-joez-el-gibbor-Abi-ad-sar-shalom is translated in the footnote as, "Wonderful in counsel is God the Mighty, the everlasting Father, the Ruler of Peace."
It is evident here that this is not a series of names interpreted by some but just a long name. More importantly, we could clearly notice here that the "God the Mighty" or "Mighty God" referred to who is also "Wonderful in counsel" is none other than "the everlasting Father" Himself. Taking into consideration that Jesus Christ is the "Son" of the Father (Matt. 3:16-17), He therefore, is not the Father Himself, hence, Christ is not the Mighty God.
Does it say anywhere else in the Bible that the Father is indeed "wonderful in counsel"? In the same book of Isaiah, these are stated:
"All this also comes from the Lord Almighty, wonderful in counsel and magnificent in wisdom" (Isa. 28:29, New International Version).
"And yet, you are the Father. We are the clay, you are the potter. We are all formed by your hand." (Isa. 64:8, New International Version).
Clearly then, the "Mighty God," who is referred to in the prophecy as also "wonderful in counsel" is not the Son Jesuis Christ but the "everlasting Father."
Why then is that one long name, having as its part in the term "Mighty God," mentioned in the prophecy concerning Christ? It is because the "government" or "authority" (JPS, 1999 edition) that the child (Christ) would later hold came from no less that the Mighty God who is the Father. Christ Himself proved this when He said:
"And Jesus came and spoke to them, saying 'All the authority has been given to Me in heaven and on earth'." (Matt. 28:18, New King James Version).
"All things have been delivered to Me by My Father, ... (Matt. 11:27).
Therefore, although Christ is the fulfillment of this prophecy about the child, it does not mean that He is God. It is worthwhile to note that one's state of being is not necessarily determined by the meaning attached to his personal name, much less by the meaning of the title of the government or authority he holds. Simon the apostle was named "Cephas" or "Peter" which means rock (John 1:42), and the apostles James and John, were named "Boagneres, that is, 'Sons of Thunder' (Mark 3:17). However it doesn't mean that Peter is Himself a rock and that the other two are "sons of thunder." Moreover, biblical names of person such as Eliphelet (the God of deliverance) and Elihu (whose God is ([Jehovah]) and places like Elkosh (God my bow) and El-bethel (the God of bethel) [Smith Bible Dictionary, pp. 163-167] also contains descriptions about, but no serious theologian so far claims that those persons and places are God. Going back to Isaiah 9:6, is this how Jewish scholars understand this verse which is originally written in their language-that the name in this prophecy does not indicate Christ's alleged divinity? In The Jewish Study Bible, edited by Adele Berlin and Marc Zvi Bettler, they explain, thus:
"The Mighty God ... ruler: This long sentence is the throne name of the royal child. Semitic names often consist of sentences that describe God; thus the name Isaiah in Hebrew means, 'The Lord saves'; Hezekiah, 'The Lord strengthens' ... These names do not describe that person who holds them but the god whom the parents worship. Similarly, the name ... in this v. (Isa. 9:6) does not describe the child or attribute divinity to him, contrary to classical Christian readings of this messianic verse." (p. 802).
It is clear that Pele-joez-el-gibbor-Abi-ad-sar-shalom is the "name" or the "title" (Mofatt Translation) of the authority or government or, as Jewish scholars put it, the "throne name" which "does not describe the child or attribute divinity to him" but as another scholar puts it, 'descriptive of his (Christ) office' given by the Father.
"This is not to have a name which will be a sign, like the names of Isaiah's sons (cf. 7:3, 8:1), but one which will be descriptive of the office." (Isa. 1:39, Mauchline, p. 113).