Jesus Christ is referred to as “Mighty God” in Isa 9:6 (“For there has been a child born to us, there has been a son given to us … And his name will be called Wonderful Counselor, Mighty God …”). Jehovah is referred to as “Mighty God” in Isa 10:20-21. How can this be if there is only one God (1Cor 8:4, Isa 43:10, 44:6)?
When a person has been indoctrinated into believing that Jesus did not come from God they are inclined to seize upon isolated versus in order to justify their otherwise indefensible theology. But the surrounding text plainly indicates that the one who is referred to as mighty God is given to us. The question trinitarians will inevitably avoid is: who gave us the son? Who provided the child?
While on the one hand trinitarians will insist that the Father is his own person, still, in the mythology of the Trinity there is no detectable father/son relationship between Jehovah and Jesus. That makes it virtually impossible for a person to accurately know the truth. And as I’ve pointed out in previous responses, Jesus is not only a son, but he is a carbon copy, so-to-speak.
In the first chapter of Hebrews Paul referred to him as being an exact image and representation of God himself. So, if Jehovah is a mighty God, and Jesus is exactly like Jehovah, why should it be some extraordinary thing that the Scriptures also refer to the Son as a mighty god? Especially will that be the case when Jesus returns, coming in the glory of his Father, which is what the prophecy in Isaiah is in reference to – the coming of Christ in power and glory.