That’s not quite accurate. Therapists are required to break confidentiality if they believe there is an ongoing risk to others, not because someone tells them of child abuse they committed in the past. In that sense, a confessional would probably be the same - you don’t confess to things that haven’t happened yet. You’re more likely to express ongoing risk in therapy than in confession.

If the confessor indicated that they were going to continue doing things, that’s when a confession should become reportable, if we’re want the law to be secular and equitable.