Celtic Studies focuses on the culture, history, and religions of the Celtic peoples.

Gregory earned a Ph.D. in Ireland, specializing in social philosophy and studying the cultural, historical, and spiritual dynamics that have shaped the Celtic world.​

In particular, his work focuses on forms of Celtic spirituality, examining its ongoing legacy and potential to contribute to theological and spiritual revitalization in the post-Christian era.

Additionally, his university teaching in Dublin provided him with firsthand engagement in the transmission and renewal of Celtic traditions, making his work both authentic and spiritually resonant.

Gregory is a member and participates with organizations such as the American Irish Historical Society, the Cornwall Cultural Association, and the Celtic League, which reflects a commitment to preserving and promoting Celtic culture, history, and language rights.​

By synthesizing his lived experience in Ireland, philosophical expertise, and Celtic heritage, Gregory has emerged as a leading voice in understanding the relationship between Celtic culture, spirituality, and the roots of communal identity found in Ireland, the British Isles, and beyond.