John Koessler, in his book "Dangerous Virtues: How to Follow Jesus When Evil Masquerades as Good," does a beautiful job at establishing that the standard of virtue can only be accurate if it originates from God. He carefully lays the groundwork through biblical truths and establishes immoral societal norms for the reader to take a hard look at society and themselves. If the reader is brave and humble enough, they can look to the text and see the misconceptions and excuses that have distracted humanity from pursuing real virtuous living. He gives enough perspective to distinguish between perceived righteousness and that which is genuinely virtuous regarding God's mandate.
We can identify, categorize, normalize, and even rationalize sinful acts; however, it all comes from the same source and ends with the same consequences, lesser living to the believer and death to the unbeliever. John uses the breakdown of the list of "big" sins to shed light on the rationalization of sin and the steady decline of moral standards for living. Taking the time to look beyond the symptoms and identify the real culprit behind ethical standards' decay takes us back to the solution and the original standard. Christ is the only person that can deliver us from the darkness and the excuses of sinful nature. Understanding the "big" sins can give us clarity; however, this clarity of reason should never distract us from the answer, and the ethical standard is Christ.