What is the theme of Paradise Lost Book 1?

The beginning of Paradise Lost is similar in gravity and seriousness to the book from which Milton takes much of his story--the book of Genesis, the first book of the Bible.He opens Paradise Lost by formally declaring his poem's subject, human being's disobedience towards God and the consequences that followed.The first words of Paradise Lost state that the poem's main theme will be “Man's first Disobedience.” Milton narrates the story of Adam and Eve's disobedience, explains how and why it happens, and places the story within the larger context of Satan's rebellion and Jesus' resurrection. Raphael tells Adam about Satan's disobedience in an effort to give him a firm grasp of the threat that Satan and humankind's disobedience poses. In essence, Paradise Lost presents two moral paths that one can take after disobedience: the downward spiral of increasing sin and degradation, represented by Satan, and the road to redemption, represented by Adam and Eve.

While Adam and Eve are the first humans to disobey God, Satan is the first of all God's creation to disobey. His decision to rebel comes only from himself—he was not persuaded or provoked by others. Also, his decision to continue to disobey God after his fall into Hell ensures that God will not forgive him. Adam and Eve, on the other hand, decide to repent for their sins and seek forgiveness. Unlike Satan, Adam and Eve understand that their disobedience to God does not know that their disobedience will be corrected through generations of toil on Earth. This path is obviously the correct one to take: the visions in Books XI and XII demonstrate that obedience to God, even after repeated falls, can lead to humankind's salvation.