Can a brilliant person be ignorant of something?
Yes. Ignorance does not mean a lack of brain power; even the most brilliant mind on earth can remain ignorant of many things because it has never been taught those other disciplines. If someone has not been taught a subject, they are ignorant of it, regardless of intelligence.
Les explains that ignorance does not mean a lack of brain power. You can have the most brilliant mind on earth, and he is still ignorant of a lot of things, because he has never been taught other disciplines. He uses electricity as an example: he may have a fairly good level of intelligence, but he has never been taught that much about electricity, so he is ignorant of it. The same is true with any other discipline. If we haven't been taught something, we are ignorant. That is not a downplay on our intelligence level; it is simply that they had never been taught. In the context, these Jews were religious and zealous for God, but they were totally ignorant of the things of God.
For they being ignorant of God’s righteousness, and going about to establish their own righteousness, have not submitted themselves unto the righteousness of God.