I think some things are unforgivable, such as incest or the murder of one’s child. So, those advocating for forgiveness need to back off in such cases.
Let us discuss first the issue of “advocating for forgiveness.” People who are enthusiastic about forgiveness need to be careful not to put pressure on others to forgive. The decision to forgive needs to come from the one who was offended. Regarding the “unforgivable,” we need to clarify what forgiveness is. When we forgive, we are offering mercy to a person. The emphasis is on the offending person and not on the act itself. In other words, people do not forgive the “incest or the murder of one’s child.” A person forgives those who perpetrated the actions. Not everyone would choose to forgive the offender under these circumstances. Yet, there are people who have forgiven such offenders. An example of women forgiving the father or father-figure for incest is documented in a scientific study as follows:
Freedman, S. R., & Enright, R. D. (1996). Forgiveness as an intervention goal with incest survivors. Journal of Consulting and Clinical Psychology, 64(5), 983-992.
Regarding the issue of forgiving the murderer of one’s child, Marietta Jaeger is well known for her forgiving the murderer of her child. You can view some of her presentations on YouTube.
