Via Reddit: Morality shifting in the context of intergroup violence.

In gist, if your ingroup does things that harm others, you are likely to subsequently shift your moral attitudes away from principles that tell you that harming others is wrong, and towards principles that value loyalty and obedience.

A quote from near the end:

Although we conceive of morality shifting as motivated by the need to protect one’s identity, and thus as a beneficial mechanism to the individual, we expect it to have much more negative consequences for intergroup relations and for society at large. It can give more leeway in the mistreatment of outgroup members, or lead to their exclusion from the scope of justice (Opotow, 1990), reducing the chance of seeing such mistreatment as violating principles of harm and fairness. Morality shifting can thus be seen as a mechanism that allows people to make a virtue of evil (see Reicher, Haslam, & Rath, 2008). Once the shift occurs, further actions are even more likely to be interpreted from a loyalty/authority perspective rather than from a harm/fairness perspective.

This seems like it may be part of the cult attractor; and is also a good reason to keep your identity small; it effectively means that your ingroup doing harmful things can act as a murder pill for you.