God has held up to Isaiah’s contemporaries a YouTube clip from 100 years in the future. It shows profligate sin characterising God’s people. But this YouTube clip turns out to be a mirror, for they are being shown a video of their own profligate sinfulness.
Why? Why give them this glimpse of the future? Because God is calling on them to repent now, to forestall his judgement, to effectively change the future by turning from their sin today so that tomorrow would be a season of God’s blessing instead of a season of God’s wrath. They refused.