"Thin places" is part of Borg's approach to spirituality that I often quote. We find these in the times, places and experiences that are a "porous" encounter with the Divine. An emotional moment, a musical event, a transcendent work of art and for me beautiful liturgy and the sacrament of the Eucharist.
These thin places can also be the times that we encounter the "other." It can be when we engage and radically welcome those that are not like us.
Borg's book "The Heart of Christianity" explores this. I found this study guide very helpful:
Read more about Borg: