The book of Isaiah has 66 chapters as the entire bible has 66 books. The bible has 39 books in the old testament and the book of Isaiah has 39 chapters that focuses on God’s righteousness, holiness, and justice for many nations that has rebelled and sinned against God as the old testament also focuses on these facts as well. The last 27 chapters of Isaiah deals with the compassion, grace and salvation of God as the New Testament having 27 books focuses on God’s Grace, compassion, and salvation, although the last book, being the book of the Revelation deals with judgement, wrath and tribulation as well. Although the New Testament describes God’s provision of salvation through the Blood of Jesus Christ. There are also messages in Isaiah chapters 40-66 concerning his judging sin and restoring his people. as the New Testament describes. Isaiah chapter 53 describes the Messiah in detail, how he died and was punished for our sins. There are great similarities in Isaiah compared with the Old and New Testament. I just uploaded 8 messages on the book of Isaiah. There will be quite a few more to complete the book. I do hope that you enjoy the teachings and the information within the book of Isaiah. The bible within the bible. There are references to the book of Isaiah in the New Testament including Jesus quoting the book of Isaiah in one of his messages. So, we can ascertain that this book is critical to our vast knowledge of prophetic oracles concerning the coming of our Lord Jesus Christ. Till next time, may God richly bless and keep you. Sincerely Bro. Hansen.