In the World, But Not of It?

Paul was addressing false teaching that trafficked in asceticism, something that historically has resurfaced often within the church. The message of asceticism is, "If you want to be spiritual, deny yourself as many earthly pleasures as possible." But is that really how God views our relationship to his creation? Didn't he call it all "very good"? Didn't he tell us to make use of the world he created, what's often called the cultural mandate? If so, then why all those verses that tell us directly, or by implication, to have nothing to do with the world? The problem is not with creation, the problem is with us.