Space and time don't exist obviously without matter. The assumption is incorrect respectively wrong that space and time are objective present or existing and the matter only overmoulding or modelling space and time. Space and time are products or effects of the objective existing matter. Insofar Einstein was putting the cart before the horse.
In mathematics you can assume or conceive an objective and infinite space and time. But nowhere in universe you can find the same conditions or properties for the space and nowhere is a clock that shows an universe-time. If you could leave the earth, space and time would modify and you couldn't perceive because you take part on the changes.
Our thoughts are determined by terrestrial clearness, mathematical ideas and many unproven theories. I can't share the view that the reality is nearly recognized.