Perhaps unsurprisingly, there's a paradox here! Kierkegaard's own indirect communication proposes that we start with the experience of those who don't believe and meet them on their own ground. His success in doing this is evidenced by the fact that, at least for some periods of the 20th century, aspects of his work became a major focus for radical thinkers of various kinds, including the non-religious and, interestingly, a significant number of Jewish thinkers (Buber, Rosenzweig, Taubes, and others).