What does Isaiah 9:13 mean?
The northern ten tribes of Israel have been dwelling in their faithlessness and disobedience to the Lord. They have trusted other gods, other nations, and themselves instead of their God. Judgement is coming from the Lord (Isaiah 9:9–11).Now Isaiah describes the coming judgment as an opportunity. He has pictured the Lord as sending the Syrians and the Philistines to devour Israel as with an open mouth (Isaiah 9:12). Following this utter destruction, Israel would recognize that nothing they have been relying on saved them. They could decide to turn back to their God and ask Him to help them. This could have been the moment they asked for restoration from the Lord.
That's not what they did, though. They did not turn to the one who brought this judgement. Isaiah shows the Lord bringing this judgment on them as a parent disciplines a rebellious child: in hopes that the child will turn and repent. Israel will not respond with repentance. Nor will they turn to the Lord for help. They will continue to turn away from Him, seeking help from other sources.