The argument is that God created light before creating Sun. How does the big bang theory resolve this contradiction?

For hundreds of years critics of the Bible have pointed out what appears to be a discrepancy in the Genesis account of creation: on the first day God created light (1:3), but on the fourth day, God separated the light from the darkness (night and day [1:14]).  The argument is that God created light before creating Sun.  How does the big bang theory resolve this contradiction?