The audience for this book is a pastor who is leading or working in a church that does not affirm homosexual behavior, but also recognizes that the church has been quite bad at interacting with LGBTQ+ folks and believes that a new path needs to be forged. To that end, the book is largely pastoral in nature. Practical examples and hypotheticals abound. There's an opening section that lays out a theology of human sexuality. For a pop-level treatment of a complex subject, that section is good. And it serves as the foundation for the posture that churches can take on this issue.
In short, Miller insists that sexual sin is not greater than other sins, which means that we give the same kind of grace here that we would give to someone dealing with any kind of sin. The basic posture is compassion and a view to understanding people before making quick judgements on them and their lives. He would rather see Christians be so compassionate and caring that they are misunderstood as approving of homosexuality than to see Christians be so firm in their opposition that they forget to show compassion, care, and grace.
He may be unique in stating that while he does not believe scripture affirms homosexual behavior, he thinks this is a secondary issue. He counsels that local and denominational leadership should be on the same page, but that we should not presume that those who affirm are outside of God's grace.
The key issue, to my mind, is what we do and do not call sin. Miller acknowledges that attraction itself is not something that can be helped and may not be sin. But churches will split on whether to approve of homosexual behavior in committed relationships and marriages. The questions at stake are things like: who can be a member of a church? Who can lead and pastor a church? How does someone who has same-sex attraction fit into the life of the church?
Probably a good book for elders to read as well.