Quote in context:
Marcus Borg has written a widely helpful book about the need for Christians to retrieve the correct understanding of Jesus, which, he claims, would be a much more appealing picture of Jesus. He titled the book Meeting Jesus Again for the First Time. I think the same can be said about the need many Christians feel to retrieve their mystical traditions: they need to become mystics again for the first time. Karl Rahner, one of the most respected Catholic theologians of the past century (and my teacher!), recognized this in a statement that has been repeated broadly: “In the future Christians will be mystics, or they will not be anything.”
When Buddha refused to talk about God in order to make way for the experience of Enlightenment, he was making the same point, but even more forcefully, that Rahner was getting at in his insistence that Christians must be mystics: “God” must be an experience before “God” can be a word. Unless God is an experience, whatever words we might use for the Divine will be without content, like road signs pointing nowhere. Buddha would warn Christians, and I believe Rahner would second the warning: if you want to use words for God, make sure that these words are preceded by, or at least coming out of, an experience that is your own. . . .
To put this more in our contemporary context, Buddha has reminded me and all of us Christians that any kind of religious life or church membership must be based on one’s own personal experience. It is not enough to say “amen” to a creed, or obey carefully a law, or attend regularly a liturgy. The required personal experience may be mediated through a community or church, but it has to be one’s own. Without such a personal, mystical happening, once cannot authentically and honestly call oneself religious.