Who says modern religion cannot be material, speculative, and science-friendly?
Thank you for this thoughtful book review, Ryan. I'd like to respond to your particular concern expressed here: “Still, I am concerned that by emphasizing the far future, sacralizing technology, and even possibly seeking a disembodied existence, we aim beyond the mark.”
In the Mormon Transhumanist Affirmation (https://www.transfigurism.org/library/core-texts/affirmation), which is a part of the MTA's constitution and supported by each association member, we affirm a belief that science and technology are "among the means ordained of God" for the achievement of various long-anticipated salvific events, including immortality, resurrection and eternal life. The "among" in this statement is important. While we think that science and technology have an important role to play (indeed, the very definition of our species depends on them), we do not believe that they are sufficient on their own for achieving God's purposes. Other essential ingredients would include faith, hope, love, and a host of other virtues that we admire and seek to follow in Christ.
I am not aware of any Mormon Transhumanists who would support the practices you are concerned about. There may be some, but I feel confident in claiming:
1) Nearly all Mormon transhumanists are interested in exploring ways that core beliefs about future events, such as human longevity, immortality, and resurrection, might be achieved with help from science and technology, but they also are deeply concerned about near-term events and risks faced by humanity, as well as the common struggle of being committed disciples of Christ in our daily walk. Any emphasis on concepts that may be neglected by more traditional religionists should not necessarily be construed as a disregard for the fundamentals.
2) Generally speaking, I've seen a more sober treatment of the potential dangers and pitfalls from the misuse of technology from transhumanists than I've seen from general audiences, who tend to be less clued into the many potential failure scenarios and existential risks faced by humanity in this era of accelerating change. Far from being mere technological cheerleaders, transhumanists tend to be more aware of the myriad ways that technology could be misused, exploring exotic failure scenarios rarely contemplated by non nerds. We think of technology as a powerful tool that can do much good and much harm. From my vantage point, it seems that Mormon transhumanists are even more keenly aware of various ethical quagmires in technology than secular transhumanists are.
3) Although we sometimes explore the possibility that current or future humanity may exist within a computed world (sometimes referred to as the simulation hypothesis), we agree that embodiment is an essential aspect of our existence that would not be any less important if we were to discover other computational substrates besides our own. Whatever such a 'simulated' existence might mean, if it were not just as relational, interactive, meaningful, and consequential as our present embodied existence is, it would be a curse rather than a blessing. It is also worth asking the question: how do we know that we aren't in a 'simulation' now? I believe this question can't be answered with absolute certainty or proof, and yet I also believe that embodiment is an essential aspect of our existence. In other words, simulation and embodiment are not mutually exclusive.
I hope that this response has helped to alleviate any concerns about our commitment to the core concepts that you mention. Thanks for your time and consideration.