The concept fascinates me and unnerves me at the same time. It is not something of which the bible explicitly speaks and yet it seems that the concept is there and that several people in the bible had their own thin places. If you think of Mount Sinai, Mount Carmel, Jacob and his ladder, and Jesus in the Garden of Gethsemane you will get a picture of what I mean. Perhaps it is not that the places have particular significance but that the places come to have special relevance for a person or for people in general.
I have a few places where God has spoken in unique ways. These are places where His voice was a little more clear and He has spoken more often. They are places to which I return to hear from Him again. It is not that He always speaks at such places; for He can be just as silent in such places as any other. It is not that these are the only places where one can hear from God. They are, however, places to which I return with increased expectancy and with an increased desire to listen. Perhaps that is the purpose of this metaphor in my life. Mark D. Roberts has this to say about the concept.
If you want to use the thin place metaphor, then you might want to say that the purpose of thin places is to help us realize that all places can be thin. Or, better yet, perhaps the purpose of a thin place is to train us to make the other places in our lives thinner. Moreover, when we realize that the Spirit of God dwells within us, we will come to believe that we are called to be thin places, as God makes his presence known through us.*May you seek places in your life where you might find a greater depth of connection with God. May there be enough thin places in all of our lives to spur us on to love and good deeds.
* For some helpful theological reflection on the concept of "thin places" see Mark D. Roberts Blog series on the topic. This is where I found this particular definition. http://www.markdroberts.com/htmfiles/resources/thinplaces.htm