Wanting to focus on the gospel this year and wanting to spend more time in the Old Testament, the book of Isaiah seemed to be a perfect book to cover. Many interpreters in history have called Isaiah an evangelist, more than a prophet, because of how well the book describes Christ. Also, I've been wanting to know how to address the moral decline we are seeing around us.
For this year, we'll be looking at sections of Isaiah together.
In Isaiah 1, he first indicts Israel for her sin (1:1-9). She has become dull, diseased, and desolate because of it.
Because of her sin, she has tried her own remedy: ritualistic religion (1:10-15). This aggravates God's wrath.
God humbly announces gospel, that he will draw close to them again if they wash themselves, stop doing evil, learning to do good, and seek to do justice (1:16-20). He calls his people to do some basic reasoning; option one is to choose repentance and get blessings; option two is to choose rebellion and be eaten by the sword.
God wants repentance.
Finally, God through Isaiah says, "here is where you are and here is where you are going." You are a whore, though you were once a beautiful bride. You are going to be taken captive soon because of your whoredom.
In conclusion, Isaiah one is basically the gospel: your sin has ruined you and you cannot fix it yourself, but God will so graciously restore you if you only wash and return.