Quite often the pattern of heresy is magnify a theological truth or method way out of proportion. Hersey usually begins with an error and then grows into a full theological construction. However once a heresy has been formally identified it can still (to some degrees) be useful.
1. There might be something under-emphasised in traditional theology that needs to be focused on again
2. Often the truths heresy denies haven't been properly explained or defended, heresy gives you fresh eyes to enjoy and promote them again
3. Combating heresy reminds you that traditional theology itself is "a process of wrestling with God"
4. Combating heresy gives you a wider cultural and theology insight into what's being valued, rejected and questioned by the wider culture
[Figures de la Bible, Gerard Hoet (1648-1733)]