There are many approaches to interfaith understanding. Most of them agree that integrity is essential; that is we have to understand any one religion on its own term and not domesticate its teaching to suit our own understanding for whatever reason.
Integrity in this area is especially important in comparative studies between religions so that we do not distort any religion to contrast or conform with another according to whim.
Paul Knitter, who professes to be a Roman Catholic and a Buddhist (his blog titles 'How a Buddhist Christian sees it'), in his lecture 'Only One Way?' (H/T: Justin Taylor) proposes that the translation of Buddhism's Sunyata concept is pointing to the God to whom is the reference of Christianity.
The Union Theological Seminary's professor invokes the translation of Sunyata as "InterBeing" as a reference to the relational Trinity. As he wrote in his book:
"Thich Nhat Hanh, a modern practitioner, scholar, and popularizer of Zen Buddhism, translates Sunyata more freely but more engagingly as InterBeing. It's the interconnected state of things that is constantly churning out new connections, new possibilities, new problems, new life." (p.12)
"...to believe in a Trinitarian God is to believe in a relational God. The very nature of the Divine is nothing other than to exist in and out of relationships; for God, "to be" is nothing other than "to relate." That, among other things, is what the doctrine of the Trinity tells Christians. (p.19)
"To experience and to believe in a Trinitarian God is to experience and believe in a God who is not [...] the Ground of Being, but the Ground of InterBeing! [...] God is the activity of giving and receiving, of knowing and loving, of losing and finding, of dying and living that embraces and infuses all of us, all of creation. Though every image or symbol limp, Christians can and must say what Buddhist might agree with---that if we're going to talk about God, God is neither a noun nor an adjective. God is a verb! With the word "God" we're trying to get at an activity that is going on everywhere rather than a Being that exists somewhere. God is much more an environment than a thing.
"And therefore, if we Christians really affirm that "God is love" and that Trinity means relationality, then I think the symbol Buddhists use for Sunyata is entirely fitting for our God. God is the field---the dynamic energy field of InterBeing---within which, as we read in the New Testament (but perhaps never really heard), "we live and move and have our being" (Acts 17:28)."
(Paul F. Knitter, Without Buddha I Could not be a Christian [UK: Oneworld, 2009], p.19-20. Emphasis original.)
For Knitter to make his case, it is fundamental that his understanding of Sunyata as InterBeing is correct. And it is on this fundamental level that I have a question to raise: Is Knitter's equating Sunyata as InterBeing valid?
Knitter himself acknowledges that this equation is the product of Thich Nhat Hanh's "free" translation. In Chinese, Sunyata is simply translated as 空, which means "emptiness" or "void". Hence the famous verse from the Heart Sutra, "色即是空, 空即是色," ("Form is emptiness; emptiness is form") to which Knitter mentioned in the lecture.
Of course, how should Sunyata be understood is still a debate among the different Buddhist sects. Nonetheless, what we can be certain here is that Knitter chooses to use a free translation to draw out conformity between Buddhism and Christianity. He disregards the question over the validity of this translation and uses it anyway.
Besides, is the Suntaya really means interconnectivity among beings? If so, then according to the Heart Sutra, interconnectivity among beings is void. ("不生, 不滅, 不垢, 不淨, 不增, 不減。是故空中. 無色, 無受, 想, 行, 識. 無眼, 耳, 鼻, 舌, 身, 意. 無色, 聲, 香, 味, 觸, 法. 無眼界. 乃至無意識界. 無無明. 亦無無明盡. 乃至無老死. 亦無老死盡. 無苦. 集. 滅. 道. 無智, 亦無得." Translation: "The void is without beginning, ending, form, embodiment, consciousness, sensation, thought, deficiency, completeness, etc." Simply said, the void is nothing.)
The Sunyata refers to the interconnectivity that has nothing and is nothing. It is ontologically impersonal.
If this is true, then I have another question to raise: If Suntaya refers to the impersonal interconnectivity among beings, how then can Knitter proposes that it is an equation to the Trinitarian God, who is fundamentally recognized in Christianity as personal?
One can see that Knitter's intention is to point out convergence between Buddhism and Christianity. However, in the way he did it, there are violations done on both Buddhism and Christianity. On one hand, Knitter knowingly used a free translation to represent Buddhism's Sunyata concept, while on the other hand, he deprived Christianity's Trinity from its nature as a personal being. As mentioned above, there are many approaches to interreligious understanding; is this how a Buddhist Christian sees it?