It is easy to slip into the notion that there are multiple different categories of sin. This is the idea behind "acceptable sin" and "unacceptable sin" that most people embrace most of the time. The thinking that certain sins are worse than others, in such a way that place sinners in different categories with respect to God than other, is fueled by a lack of the understanding that all the sin that humanity has ever committed belongs to the same category. Sexual sin does not inhabit a different realm of immorality than gluttony, anxiety, speeding in traffic, or stealing cookies.
Do you think you are different? Most people, most of the time will read the New Testament this way: The Pharisees, those despicable, arrogant opposers of Jesus, represent the religious establishment. They oppose the righteousness of God when it comes to them, they legalistically split hairs on the basis of over-educated obsession with Scripture, and they come down with condemnation for those who don't live up to their standards.
The tax-collectors, prostitutes and adulterers, however, were on Jesus' side. They received what he had to bring them, he befriended them and revealed an affection for those cast off by society as "immoral." This(and here's the big lie) is because their sin is of a different type than the Pharisees.
What's actually going on in this paradigm is a lot more tricky and sinister than a first glance gives away. We construct a view of sin that allows us to place others, those we disapprove of, in a place that we are not: having uniquely violated the law of God. (Isn't it strange how rarely people who talk of Pharisees will locate themselves in that position?) This gives us the ability to place ourselves in the category of "approved" or at least "not so badly condemned." Ever heard this: "Yeah, I'm not perfect or anything, but at least..."
The big secret that few people want to admit about the New Testament is that the Pharisees and the "sinners" with which Jesus ate are actually the same people. That's extremely important. That's also devastating to a lot of people, including the part of you that has embraced this paradigm: that the Pharisees are "those people, the religious establishment, the people that have their lives together, the people who dress religiously..."
So two categories of sin are created, moralistic vs. senusal. Legalism vs. licentiousness. The understanding once you've constructed this Scylla and Charybdis paradigm is that if we go too far in one direction, we will slip into the category that we weren't concentrating on. The key to being aware of both and navigating a perceived middle ground. The solution is to blend of two different concepts in your teaching: don't be too legalistic, but don't only concern yourself with the grace of God either(because grace is primarily a sweet tone of voice and an uplifting word, and how is that ever going to deter sinners from their iniquity?) God wants to apply a "don't be bad" solution to one and "don't be judgmental" to the other, as if the sexually immoral person and the one judging that person were doing something fundamentally different. The message of gospel comfort for one sinner and the law for the other. Or better yet, two different kinds of moralism: one custom-tailored for each, and the Gospel is altogether history because, hey, they're already "saved."(whatever that means)
The implications of this are staggering: the Cross is sufficient for one of them, not both(or all, if we continue down the road logically and endlessly divide up sin into millions of categories, with a different approach to dealing with each), and therefore the Gospel should only be preached, at most, half the time. For those who seem not to heed the proclamation of the Cross, or who take the initial "faith step" but don't seem to be walk in transformation, we need to add things, adjust the message.
I'm certainly all for a nuanced understanding of what the Gospel sounds like in different situations. But it remains just that: a sounds like. Substance does not change.(This incidentally gets to the bottom of any and all conflicts concerning cultural engagedness and how we express ourselves as "separate" and not in conformity with the world. For Dr. Peter Masters, who may normally have useful things to say, in this case doesn't seem to grasp that his culture of Puritan "old" Calvinism is just as much derived from worldly sources as the culture of "new" Calvinism that contains t-shirts and hip-hop music. Again, sinful t-shirts or sinful suits?...take your pick.)
What possibly could be at work in the mind that thinks in the Scylla/Charybdis categories? Maybe it has a completely befuddled definition of grace and the Gospel. Or maybe it doesn't actually believe the Gospel, simply wants to be understood as a godly and moral person. Maybe it doesn't grasp that the difference between justification and sanctification is philosophically useful but actually nonexistent. Maybe it is so concerned with its external perception and its subjective categories that it thinks there are actualy multiple problems at work in the world causing humanity's suffering, and therefore multiple solutions are required. Whatever the case, the end result is always the same: man is able, by force of intention and will, to cleanse himself from sin, and therefore Jesus is an unnecessary afterthought.