If there is only one God, then why do different spiritualists have differing conceptions of the divine?

Answer: The differing conceptions of the divine result due to different perspectives from which God is perceived.

The various divine conceptions in the world’s wisdom-traditions can be classed under three broad categories:

1. The all-pervading energy (Brahman): What quantum physicists call as the one energy-sea that underlies everything in the universe, what the mystics refer to as the impersonal oneness of all things and beings, the Vedic scriptures explain that to be Brahman, the all-pervading energetic effulgent light.
2. The inner guide (Paramatma): Many spiritual traditions talk about an aspect of God immanent within us. What the Christian tradition refers as the empowering Holy Spirit, the Vedic scriptures call as the Paramatma, the inner guide who mediates the interactions between the spiritual soul and the material body.
3. The supreme person (Bhagavan): Saints throughout history have lovingly connected with God as the Supreme Person. That Lord whom Moses called Jehovah, whom Jesus referred to as his father in heaven, whom Mohammed praised as Allah, the Vedic scriptures reveal as Krishna, God manifesting as the all-attractive transcendental Supreme Person.

The Shrimad Bhagavatam (1.2.11) explains in one succinct sutra-like verse that three conceptions are multiple manifestations of the one Absolute Truth: “Learned transcendentalists who know the Absolute Truth call this nondual substance Brahman, Paramatma or Bhagavan.” Here’s an analogy to illustrate this unity-in-diversity.

Three rural students arrive one night at a railway platform with their teacher eager to have their first sight of the train. After a long wait, when they see a bright light in the distance, the first villager asks their teacher, “Is that the train?” When the teacher nods, he departs, convinced that he has seen the train. When the train comes closer, the second student notices the engine – the form behind the light – and asks, “Is that the train?” When the teacher nods again, he too leaves, confident of having seen the train. When the train finally comes into the station, the third student sees the train in its fullness with its driver and multiple compartments and passengers and, with the encouragement of his teacher, even meets and befriends the driver.

Analogically, the bright front-light of the train represents the effulgent spiritual substratum, Brahman and the engine with its concrete shape represents the localized, personalized divine substance, the Paramatma. The third student’s experience is akin to meeting the Supreme Person, Bhagavan, and developing a personal relationship with him. The teacher represents the wisdom-traditions, which give an answer commensurate with the seeker’s level of patient commitment.

Thus, a proximate, holistic vision reveals a three-in-one Absolute Truth that integrates both the immanent and transcendent aspects as well as the personal and impersonal features.