It's easier than you might think. In days gone by people sinned rather profusely but for the most part these sins tended to be private affairs conducted in secret. Even those sins requiring the cooperation of another tended to be carried out behind closed doors. Some sins which had to be performed in public were often shrouded in ritual and mystique designed to obscure its true nature. Who would ever guess that a lavish banquet honoring some public figure was in reality a cover for a multitude of sins not the least of which was gluttony?
Mind you, really big sins requiring the collusion of many sinners have always been with us. This is why men invented politics. That need not concern us here for politics is not generally regarded as a heresy, merely a proximate occasion of sin. Our concern here is rather to examine how those private and furtive sinful acts may be transformed into a heresy.
Bedding another person's spouse is adultery and it is one of those sins usually committed in private. However, if a third person is involved performing the role of matchmaker then the private sin becomes the basis for a profitable business. Transforming the sin into a heresy gives the sinner a whole new air of respectability. What was once a sordid little affair conducted in private for the adulterer becomes for the adulterist a progressive challenge to the boundaries of stolid morality. This has many advantages. The adulterist gains an air of quasi respectability that would otherwise be denied by anyone with common sense. Even their opponents gain in the transaction. Where once sin had to be countered by preaching, good counsel and good example, a heresy opens new vistas.
Let's face it... confronting a close relative who is contemplating their second marriage is a painful process. You risk alienating the relative and dividing the family. However if that single relative can be morphed into an entire social group, however ephemeral, confronting them becomes easier. It is no longer personal and painful. This can have unfortunate consequences. By objectifying and demonizing your relative you push them away from the family and towards identifying with some ephemeral social group of adulterists. Mind you, they will likely come up with a snazzier name for it by that time affording you endless opportunities for arguing over the name. This should distract you from the pain of realizing that you have just lost a brother.
You should begin to realize why it is necessary to jail Mary Wagner. So long as people can be kept to arguing whether it is pro choice or pro life or whatever then everyone is safe. So long as it is a political issue involving advocacy groups on either side then no one need worry. However, one woman walking into a clinic to talk to another woman about the decision she is making is about as dangerous as you can get. The government understands this and acts accordingly.
We need to follow her example and begin to deal with people personally. The Church exists as a refuge for sinners. It is where they learn slowly, step by step, to wean themselves of their attachment to sin and grow closer to God. Every time we push a sinner away from the Church we strengthen the enemy. We need to stop treating our brothers and sisters, our neighbors, as members of some heretical group and approach them as persons.
When the sin involved is one that we ourselves might commit if tempted, then it is easier to show compassion towards a sinner. We understand their motives and temptations. What of sin we do not understand or which provokes a feeling of revulsion in us? This is the easiest to transform into a heresy. In our conceit we imagine that God shares our emotional reactions and the sin that provokes such revulsion in us is far worse than the one we ourselves have committed which gave us such pleasure. In short, we consider our own sins to be moral failings that require repentance but others' sins, especially ones we don't like, are irredeemable moral depravity and evidence of some conspiracy. We are sinners but they are heretics.
Really? The grand conceit of this is that we imagine that God will put up with us but not them.