This is attributed to Pierre Teilhard de Chardin in The Joy of Kindness (1993), by Robert J. Furey, p. 138; but it is attributed to G. I. Gurdjieff in Beyond Prophecies and Predictions: Everyone's Guide To The Coming Changes (1993) by Moira Timms, p. 62; neither cite a source. It was widely popularized by Wayne Dyer, who often quotes it in his presentations, crediting it to Chardin, as does Stephen Covey in Living the 7 Habits : Stories of Courage and Inspiration (2000), p. 47. Such statements could be considered paraphrases of Hegel's dictum that matter is spirit fallen into a state of self-otherness.  Or any number of thousands of similarly vague quotes by hundreds of predecessors. 
Disputed 
Variant: We are not human beings on a spiritual journey. We are spiritual beings on a human journey. 
Variant: We are not human beings having a spiritual experience; we are spiritual beings having a human experience.
                                    
“We are not human beings in search of a spiritual experience. We are spiritual beings emersed in a human experience.”
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Wayne W. Dyer 92
American writer 1940–2015Related quotes
“We are not human beings on a spiritual journey. We are spiritual beings on a human journey.”
                                        
                                        Pierre Teilhard De Chardin, in The Phenomenon of Man [Le Phénomène Humain] (1955); Covey quotes this in Living the 7 Habits : Stories of Courage and Inspiration (2000), p. 47
Variant: We are not human beings on a spiritual journey. We are spiritual beings on a human journey.
A paraphrase of De Chardin's statement which has also become misattributed to Covey. 
Misattributed 
Variant: We are not human beings having a spiritual experience; we are spiritual beings having a human experience.
                                    
“You are an infinite spiritual being having a temporary human experience.”
“Science depends on outer experiment. Spirituality depends on inner searching and seeking.”
                                        
                                        Songs of the Soul (1971) 
Context: Science depends on outer experiment. Spirituality depends on inner searching and seeking. A scientist discovers the power that very often threatens even his own life. A spiritual seeker discovers the power that guides and moulds his life into a life of divine fulfilment.
                                    
                                        
                                        As translated by Alan R. Clarke (1996). 
By The River Piedra I Sat Down and Wept (1994)
                                    
Source: https://www.goodreads.com/author/quotes/14108295.alexis_karpouzos?page=2