The nature of Mind is originally pure, but no one has a mind true and sincere
From River of Fire, River of Water by Taitetsu Unno, p. 196-197:
“I once heard an eminent Zen master say that even Hitler had Buddha-nature but unfortunately it was never manifested. This may be valid from the Mahayana viewpoint, but Shinran would disagree. Because of his realistic grasp of the limited, foolish, and defiled nature of man, he saw even himself as completely lacking in Buddha-nature. What does this mean in the context of the universality of Buddha-nature?
The Shin position is that Buddha-nature is not a given, nor is it an abstract doctrine. The same holds true for the mind that aspires for enlightenment (bodhicitta). It too is virtually non-existent in the average person. Shinran states his understanding in the following verse:
Karmic evil originally has no form;
It comes from delusions and inverted thinking;
The nature of Mind is originally pure,
But no one has a mind true and sincere.
Although “no one has a mind true and sincere,” once a person is awakened by the light of true compassion, the aspiration for enlightenment becomes vividly real and Buddha-nature for the first time becomes a dynamic reality.
All this, however, is contingent upon true entrusting that is Amida’s working being manifested in our life. True entrusting is impossible coming from a karma-bound human being; it becomes true and real by virtue of Tathagata that permeates the world.”
The full title of Taitetsu Unno’s book is River of Fire, River of Water. An Introduction to the Pure Land Tradition of Shin Buddhism (1998)