Our thoughts may be transparent, but our fundamental selves are not.
Thus God knows what we are thinking, but does not know our "hearts".
This is important to recognize, because it explains why so many people are incarnated into this mortal life, who seem to be evil; and evil in an apparently unredeemable way. Who appear to be utterly incapable of love, or to hate love - and who behave accordingly.
If the human heart/ soul/ ultimate-self were transparent to God - i.e. if God knew for sure that such people were structurally incapable of love - then there would be no reason for innately-evil people to be incarnated into mortal life...
Because mortal life could do such persons no good, because they are incapable of learning the lessons of this world; and because there are many reasons for hope-lessly evil people not to be incarnated - since they cause so much suffering, and may induce other people to engage in and desire evil.
This world and life therefore make best sense if we realize that God does not know our fundamental nature, cannot see into our "hearts; and cannot be sure of any individual that he will not at some point in his life; learn-spiritually, repent, and eventually accept the gift of Salvation.
Such is one reason why this world contains individuals who truly are greatly evil, some who were (apparently) born evil, some who seem incapable of good - even some who, in their hearts (if anyone but knew that) may be totally evil.
NOTE: It is likely that very few of the famously historically evil leaders were innately and totally evil, since this would usually be a bar to social success and power. Past societies were also alert and keen to exclude or eliminate (one way or another) such persons. Total evil is most likely to be seen among children, youths, and among obscure adults; and is probably much commoner in modern societies - where value-inversion is positively-regarded, official and enforced.
