Even though she knew rationally that she was inculpable for her sister's suicide, she still could not help feeling that she could have done something to prevent it.

culpable, exculpate, exculpatory, culprit, inculpable, and inculpate.

Depending on which meaning of "good", some 10 letter words could be: acceptable, stupendous, inculpable, proficient, satisfying, charitable

The root word "culpa" means fault or blame in Latin. It is often used in legal contexts to refer to responsibility or culpability for a wrongdoing.

That is the whole point of Creation and of our lives. God deliberately and carefully reveals His existence to some degree, while hiding it to a greater degree, in order to set the stage for the purpose of life.

If God revealed His presence to a much geater degree, we'd have no choice but to serve Him, like angels or robots. On the other hand, if He hid Himself and His will to a complete degree, we might be inculpable even if we lived like animals with no laws at all.