Isaiah 65:1-9 is the First Reading appointed for the 2nd Sunday after Pentecost in the Year of Luke. There seems to be little connection with the story of the Gerasene demoniac in Luke 8 aside from the fact that dwelling in caves and places of the dead is present in both. Nevertheless, it is a word of Law to any who would provoke God with secret practices that lead one away from the Living God. It will be the preacher's challenge to preach this.
(The following questions attempt to get at the foundational question for Law and Gospel preachers, i.e. How is the Word functioning in the text? These questions are best used with other fine sets of questions that have other concerns. For more on this method and on Law and Gospel preaching in general see my brief guide, Afflicting the Comfortable, Comforting the Afflicted, available from wipfandstock.com or amazon.)
1. How does the Word function in the text? Undoubtedly the Word is mainly Law here, lifting up the multiple ways in which a "rebellious people" are following "their own devices." "I will repay; I will not keep silent," says the Lord. There is, however, a brief word of gospel at the end of the passage. The Lord makes a distinction between those who have been condemned and the "chosen" and "my servants." To these come a gospel word about homecoming and an inheritance.
2. With whom are you identifying in the text? We could identify with either the faithful or the unfaithful, or both. If we identify with the unfaithful, we shall need to ask in which ways have we followed our own devices and left the path the Lord has set out for us. If we identify with the faithful, we will offer a sacrifice of praise for God's abundant mercy.
3. What, if any, call to obedience is there in this text? Much of this text could be understood as an implicit call to obedience. We could understand this passage as speaking to us about forbidden practices as God's people. While we may not be engaged in these kinds of cultic practices, we could all readily recall ways in which we, as God's people, do not always engage in practices which are life-giving.
4. What Law/Gospel couplet is suggested by this text? Specific couplets can be identified using the terms in this text. Some examples: judged/forgiven; repaid for iniquities/redeemed; abandoned/embraced.
5. Exegetical work: This text is a contrast to many prophetic texts in that it does not condemn the people for oppressing the poor as is often the case. Here rather is condemnation for cultic practices: burning of incense to the spirits, necromancy, and the eating of unclean flesh. God makes it clear that these practices will not be tolerated amongst God's people. Claus Westermann, in his classic commentary, illuminates the statement in verse 5: "Verse 5, too, refers to an idea that was alien to the worshp of Yahweh - that of contagious 'holiness' due to the cult, which is thus equivalent to cultic impurity." (The OT Library series, Isaiah 40-66, p.401). Westermann also helps us understand what is going on in the last verses: "This verse [v.8] shows how ch. 65 effects the transition from the earlier prophecy of doom to a new form of the announcement of God's action, one which at one and the same time announces salvation to some and judgment to others. This was an extremely momentous change, because a divine intervention at once bringing ruin upon one section of the nation and salvation upon the other cannot possibly be conceived in terms of history." (Ibid., p. 404).
6. How does the Crossings Community model work with this text? Cathy Lessmann does a nice job of taking the phrase "Here I am," and showing its power to be both Law and Gospel. On one hand, this announcement brings us fear for when God shows up our sins are exposed. On the other hand, this announcement also brings joy because when God shows up as Christ on the Cross our sins are forgiven. See the entire analysis archived under its reference at crossings.org/text-study.
Blessings on your proclamation!