If any belief system, whether secular or religious, sets out to do any of the following, I consider it bad for humankind:
a) It advocates harm to others, either as punishment or for merely disagreeing with it;
b) It is not based on empirical observation;
c) It claims that other belief systems are false on purely stated/a priori grounds, rather than empirical grounds (e.g. that they make no regular predictions).
I believe this list of criteria, if practiced, will solve humanity's problems. However, people are far too fond of doing the opposite:
a) Advocating harm to those who disagree or who do wrong as decided in an arbitrary set of rules;
b) Base things on what their parents or other elders told them;
c) Love stating that others are in moral or spiritual jeopardy for failing to recognise the legitimacy of the system, rather than on empirical (visible/measurable) grounds;
Moreover, I believe that any system which has the following requirements is inherently a cult and bad for humanity (whether a "scientific" system or a "spiritual" system:
a) It says that it is forbidden to question the leader(s) or belief system that they espouse;
b) it prohibits rejection of the system once it is accepted as "true"
c) it has special behavioural requirements such as dress or other visible markers to distinguish its practitioners as being "special" or "in touch with" some "higher" truth claims.