Dr. Sam Parnia is a British American critical care physician and a leading resuscitation scientist. As an associate professor of medicine at the New York University (NYU) Grossman School of Medicine and the director of Critical Care & Resuscitation Research at NYU Langone, he provides the primary scientific backdrop for 18 Days in Heaven. Parnia is the principal investigator of the AWARE studies, which examine consciousness during cardiac arrest. His research gives empirical context to the book’s claim that a person can have a lucid, reportable experience while clinically near death, offering a degree of scientific plausibility to Poirot’s testimony.

Leading international research collaborations since the 2010s, Parnia has established institutional authority in the field of NDEs. His methodology involves prospective, multi-center protocols that use standardized post-resuscitation interviews and in-hospital physiological monitoring, including EEG, to correlate the quality of resuscitation with patients’ recalled experiences of death. This rigorous clinical design seeks to move the study of NDEs from anecdotal reports to systematic data collection, providing the scientific context that Poirot draws upon when discussing the possibility of conscious experiences during clinical death.

Parnia’s findings suggest that structured and lucid experiences can occur during cardiac arrest, a state where the brain is typically thought to be non-functional. His work provides a clinical framework for Poirot’s account, situating the memoir's spiritual testimony within a broader, ongoing scientific inquiry. However, debates persist within the scientific community over the mechanisms behind these experiences, including the possibility of residual brain activity, the timing of memory formation, and the limits of current monitoring technology. Parnia’s research, while groundbreaking, represents one part of a complex and evolving field.

Brian Simmons is an American ministry leader and the lead translator of The Passion Translation (TPT), a version of the Bible that has gained a wide readership within charismatic and Pentecostal Christian circles. A former missionary and pastor, Simmons founded Passion & Fire Ministries to promote what he describes as a more heart-level, affective engagement with Scripture. His work is significant to 18 Days in Heaven because Poirot frequently quotes TPT alongside more conventional translations like the New International Version and New Living Translation, meaning that Simmons’s distinctive linguistic and theological emphases help shape the book’s message.

Poirot interweaves citations from TPT to interpret key Christian doctrines, such as the believer’s union with Jesus and the love of God the Father. The translation’s stated goal is to add “passion” to the reading of Scripture, an aim that aligns with the book’s emotive and experiential tone. For the book’s target audience, the use of TPT reinforces its emphasis on a personal and experiential understanding of biblical teaching.

However, Simmons’s work is also a subject of significant controversy. Many biblical scholars and theologians have critiqued TPT for its single-translator methodology and its expansive renderings, which often add interpretive glosses not found in the original Hebrew, Aramaic, and Greek texts. These concerns were highlighted in February 2022 when the popular online Bible portal Bible Gateway removed TPT from its platform. Because Poirot relies on this translation, some of the scriptural language used to support his testimony reflects a contested and highly interpretive translation philosophy, providing important context for understanding the book’s theological framework.

Dr. Bruce Greyson is a psychiatrist and professor emeritus at the University of Virginia, where he was a co-founder of the International Association for Near-Death Studies and served as director of the Division of Perceptual Studies. A pioneering NDE researcher and the author of After (2021), Greyson is renowned for developing the Greyson Scale, a standardized method for determining the depth of an NDE. His work systematically organizes anecdotal reports into recognizable patterns. In 18 Days in Heaven, Greyson’s research supplies an established clinical taxonomy for interpreting the events Poirot describes. Common NDE features that he identifies, such as the panoramic life review, a sense of overwhelming peace, altered perceptions of time, and enduring personal transformation, are all central motifs in Poirot’s narrative. Greyson’s decades of research provide a broader clinical context for Poirot’s individual testimony, highlighting similarities between his account and patterns reported across cultures and belief systems.

John Burke is the founding pastor of Gateway Church in Austin, Texas, and the New York Times best-selling author of Imagine Heaven (2015), a book that synthesizes over a thousand NDE accounts to argue for their consistency with Christian scripture. Burke’s significance to 18 Days in Heaven comes from his role as an endorser and a key figure who models a “Bible-first” hermeneutic for interpreting NDEs. His enthusiastic blurb appears on the book’s cover, framing Poirot’s story for prospective readers as a trustworthy account that Burke regards as theologically sound testimony. Burke states, “Gabe Poirot’s NDE is one of the most miraculous, awe-inspiring, and biblically confirming cases I’ve encountered” (vii). This pastoral validation supports the author’s primary goal of presenting an experience that is Jesus centered rather than merely a catalog of heavenly sights. By lending his support, Burke helps situate the book within a tradition of NDE narratives that emphasize consistency with Christian scripture.

Randy Kay is an author, NDE interviewer, and ministry leader who claims to have had his own NDE. A former executive in the life-sciences and biotech industries, Kay now writes and speaks on afterlife topics, bridging his medical and leadership background with experiential theology. As the author of one of the book’s Forewords, Kay serves as a key validator of Poirot’s testimony. He presents the narrative as Jesus centered and situates it within a broader corpus of what he considers vetted NDE accounts. His Foreword frames reader’s expectations by emphasizing the story’s scriptural fidelity and the medical improbability of Poirot’s survival. Kay also highlights one of the book’s central themes: that the ultimate purpose of the experience isn’t to speculate about heaven’s details but to foster a personal encounter with Jesus. His endorsement helps position the memoir as an authentic and transformative spiritual witness for its intended Christian readership.

Rick Renner is an American minister, author, and broadcaster who serves as the senior pastor of the Moscow Good News Church and founded a large Russian-language Christian media network. He’s well-known among charismatic readers for his popular Greek-word studies like Sparkling Gems From the Greek. His Foreword to 18 Days in Heaven helps establish credibility for its intended audience. He attests to his personal friendship with Poirot and describes having reviewed the manuscript, praising its editorial care and its focus on “[h]is revelation of Jesus Himself” rather than on heavenly spectacle (xix). His endorsement functions as a character witness, presenting the author as sincere and portraying the testimony as theologically sound from Renner’s perspective.