Christian theologian and existential philosopher Paul Tillich had a view on Buddha Nature that may serve those of us who are still unsure of nomenclature...he said that at our fundamental foundation, we are energized by the Ground of our Being, which is none other than God. But Tillich's god was anathema to most of his more conservative Christian contemporaries. Tillich argued that God is beyond God, that God is the "unoriginal source"* of all being.
This is of course an ontological question, but our anxiety, our suffering, stems from the question of our being, of what it means to be a finite being.
We are self conscious of our living and dying, and the question of What Is This prompts deep anquish that drives perhaps all of our unconscious motivations.
Tillich's Ground of Being is yet another way to understand that we already exist in a state of acceptance, of Buddha Nature, of the Unborn, and we are already supported and embraced by this ultimate acceptance.
When we begin to awaken to this reality, we find liberation! We find an end to suffering and the causes of suffering.
This is what the Buddha realized and what he meant with the first turning of the wheel of dharma--we are beings who are without ease because we strive to make this world of ours what it is not, and the only way to put an end to this painful striving is to follow the 8 Fold Path, the ultimate users guide to the universe and beyond.
If you aren't already familiar with Paul Tillich, I highly recommend you delve into his work, which I apologize for attempting to simplify here. His teachings are brilliant and profound.
*J.N.D Kelly, Early Christian Doctrines