Isaiah 48: 6-8.
6 Thou hast heard, see all this; and will not ye declare it? I have shewed thee new things from this time, even hidden things, and thou didst not know them.
7 They are created now, and not from the beginning; even before the day when thou heardest them not; lest thou shouldest say, Behold, I knew them.
8 Yea, thou heardest not; yea, thou knewest not; yea, from that time that thine ear was not opened: for I knew that thou wouldest deal very treacherously, and wast called a transgressor from the womb.
In this passage, a continuation from the previous verses, God emphasizes the stubborn spirit of His people. He has shown His people, Israel, so many things new and hidden from anyone else, and yet they persist in turning to idols they have created with their own hands, giving honor to their idols for things only God could do.
God goes on to say that He will show them new things that they have not heard before, and they will not be able to say, “Oh, well, I knew that!” God knew from the beginning the hardness of their hearts, and their desire to raise themselves in their own eyes
I need to emphasize again that God could just as well have been speaking to us today, using the same words. They are just as applicable in the Church Age as they were under the Law. We cannot point fingers at others without three fingers pointing back at ourselves.