I mean spacetime is just a construct to get around Euclidean perceptions of dimensional space. String theory and m-theory are constructs as well. They are ways of studying, understanding, and perceiving, but are they "real" or are they "artificial"?
Einstein is a good example to use here because he very much was able to extricate his rational, mathematical mind from his personal spirituality. He even had some fairly theistic worldviews, among my favorites is:
"A human being is a part of the whole, called by us Universe, a part limited in time and space. He experiences himself, his thoughts and feelings as something separated from the rest-a kind of optical delusion of his consciousness. This delusion is a kind of prison, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free from this prison by widening our circle of compassion to embrace all living creatures and the whole nature in its beauty."