This research has two primary objectives. In the first part, I touch on some remarkable similarities regarding ‘Ultimate Reality’ in three major traditions: Zen Buddhism, Eastern Christianity, and Western Christianity. I focus mainly on the teachings of Masao Abe, St Gregory Palamas, and Meister Eckhart. One of the themes draws on the parallels between the Buddhist notion of arriving at ´s¯unyat¯a, the Orthodox notion of seeking union with God through the practice of unknowing (¢γνωσ…α), and Eckhart’s notion of reaching God via “undifferentiation.” Related to this is Buddhism’s objective of leaving the false notion of self, the Orthodox aim to be liberated from creation and be united to the Creator, and Eckart’s notion of merging the highest part of the soul into non-existence. All three traditions recognize the transitory nature of the world and therefore all affirm that the perfection of humans does not consist in which assimilates them to creation, but in what distinguishes them from the created order and assimilates them to the Ultimate Reality. In the second part, I utilize neurotheology, a relatively new research field, in interreligious dialogue. I comment on some nearly identical practices in Zen Buddhism and Eastern Orthodoxy from a neuro-theological perspective, linking them to the unique religious practice called ‘speaking in tongues’. I argue that these similarities not only signify the shared evolutionary past and neurobiological present of every human being but, from a religious point of view, even indicate the same Ultimate Reality as our shared telos. My goal is to contribute to interfaith dialogue via highlighting these similarities and encouraging extended utilization of neurotheology in the field.