The notion of a spirituality of subtraction comes from Meister Eckhart (c.1260-1327), the medieval Dominican mystic. He said the spiritual life has much more to do with subtraction than it does with addition. Yet I think most Christians today are involved in great part in a spirituality of addition.
The capitalist worldview is the only one most of us have ever known. We see reality, experiences, events, other people, and things—in fact, everything—as objects for our personal consumption. Even religion, Scripture, sacraments, worship services, and meritorious deeds become ways to advance ourselves—not necessarily ways to love God or neighbor.
The nature of the capitalist mind is that things (and often people!) are there for me. Finally, even God becomes an object for my consumption. Religion looks good on my résumé, and anything deemed “spiritual” is a check on my private worthiness list. Some call it spiritual consumerism. It is not the Gospel.