The issue of how anybody knows that he or she is RIGHT has been discussed here many times
For people like dasa and rjh there is no problem: it is absolutely obvious that they, and they alone, are RIGHT and everybody else is WRONG!
For some of us who think a bit further, it is not that simple. I cannot deny somebody else the same right that I demand for myself, which is to believe what I believe. But more fundamentally, there remains often a nagging doubt that maybe they
are also right?
For me the answer has not been to find a common denominator between faiths, but rather to seek the Bigger Picture which encompasses all.
The following quote comes from a Franciscon Monk, Fr Richard Rohr, in his e-mailed daily meditation, and the question I ask is: is anybody else also seeking this Bigger Picture?
Orthopraxy, right practice, is usually distinguished from orthodoxy, doctrinal correctness. It was taught very early in world history by much of Buddhism and Hinduism.
St. Vincent of Lerin, in the year 434, was the first to define the word "catholic." His definition, called the "Vincentian Canon," was used by scholars for much of the first millennium of Christianity. It became a way to discern the true belief of the Church.
Vincent's in-house principle was amazingly simple and clear and yet almost shockingly impossible: "Now in the Catholic Church itself we take the greatest care to hold that which has been believed everywhere, always and by all. That is truly and properly 'catholic,' as is shown by the very force and meaning of the word, which comprehends everything almost universally." In other words, if it is true, then it has to be true everywhere and all the time, or it is not true!
Most of history has been content with cultural truth, denominational truth, national truth, scientific truth, rational truth, factual truth, personal truth, etc. These are all needed and helpful, but the job of true religion is to detach from them, use them in the largest possible synthesis, and find the Big Truth that is beyond any of these smaller tribal truths.
Jesus' metaphor for this Big Truth beyond our little truths was the "Reign of God" or the "Kingdom of God." Or we might say "in the light of eternity" or "in the final analysis" or "in the eyes of God." But these are all ways of moving away from tribal thinking and looking out at life from eyes other than and larger than our own. It is hard work. This larger and constantly recurring wisdom has been called the Perennial Tradition or the Perennial Philosophy. No one group owns this content, but most of us own parts of it, and for me the goal is to honor and include as many parts as I can, so that I can be truly catholic.
We see this same inclusivity in Jesus to an amazing degree. I see this as the clearest indication that one practices "the true religion." A true religion is precisely one that can teach you how to recognize and honor God everywhere, and not just inside your own group symbols.