Those are Johnny’s comments, Siebe.
Johnny wrote: “But unless we are faced with extreme difficulties under very trying conditions, we cannot for sure know that we have attained any magga phala.”
That is quite true.
– However, if one has truly attained a magga phala, no external circumstance will dictate one’s moral behavior limits set by THAT PARTICULAR magga phala.
It is only an Arahant who WILL NOT, under any circumstance, commit any akusala.
A Sotapanna, for example, is NOT CAPABLE of doing only six types of extreme akusala: killing father, killing mother, killing an Arahant, injuring a Buddha, stop following the path of the Buddha. The other one, I think is Sangha Bheda (schism in Sangha), but that is applicable only to bhikkhus.
P.S. However, that DOES NOT mean that a Sotapanna WILL DO any other akusala deeds. Those are just the ones a Sotapanna WILL NOT DO, under any circumstance.