In a nutshell
the quran is a way of life for a muslim not a non muslim
so all that is written in it is as guidance for a muslim
That particular passage (although often cited on the athiest websites, where i am assuming you got it from? apologies if wrong but coincidence? as it seemed similar the last time we 'spoke')
the passage is talking about falsehood if you will, it talks of a mirage in the desert, which a thirsty person will head towards but find it wasnt water
in th esame way a muslim can see a mirage, heads towards it only to find it doesnt exist.
the verse is calle the light, and it is od's and dont's if you will. the verse before the one you quoted talk about giving charity etc
by the way i aint a muslim scholar or anything, this is my understanding