Solzhenitsyn is plainly wrong. Or, perhaps he was equating being “bad” with being “evil”. A person can do some bad action, but on reflection they will see their error and have remorse and want to make amends otherwise they live with a bad conscience.
To do evil, a person has to first deaden their conscience. On some other thread I discuss this but I can’t recall where so I will repeat it here. To deaden the conscience, according to my late, psychopathic husband, it takes two steps.
The first step is to do harm to others (human /animal) until they feel nothing, feel indifferent to the pain and suffering of the other.
The second step is to do harm and get pleasure from seeing the pain and suffering of the other. At that point the conscience is dead.
This is a conscious, free will, deliberate choice and action and it has spiritual implications because they sever the connectivity or love between their own soul and other souls. Thus they have hate or are disconnected from others spiritually. This chasm is irreparable. They have cross the abyss from whence there is no return.