Money is a social construct to take the place of a direct exchange of goods and services. In this case it is abstract, with the money only holding value so long as society agrees on that value.
Time is an abstract construct with real world implications and relevance. It is a way for us to quantify the passage of our lives, the seasons. So again, abstract, but illusion seems an odd way to put it.
Religion seems to be a more direct idea of an illusion, as it does appear to be, as its modern and pre-modern predecessors show, entirely made up based on people not being comfortable with the unknown.