Paul instructs us to examine our lives so that we can uncover our areas of thinking and conduct that are conformed to the sinful patterns of our culture and need to be transformed by renewed minds and redeemed lives. Paul refers to the godless and sinful culture of his day as Gentile and in so doing does not reject them as a people (he in fact labored to bring the gospel to the Gentiles as the apostle to the Gentiles), but rather rejects the sinful conduct of their culture.