According to the technical definition of sin it consists in the violation of law, and in this strict sense sin may be committed inadvertently or in ignorance. It is plain, however, from the scriptural doctrine of human responsibility and the unerring justice of God, that in his transgressions as in his righteous deeds man will be judged according to his ability to comprehend and obey law.
To him who has never been made acquainted with a higher law the requirements of that law do not apply in their fulness.
For sins committed without knowledge—that is, for laws violated in ignorance—a propitiation has been provided in the atonement wrought through the sacrifice of the Savior; and sinners of this class do not stand condemned, but shall be given opportunity yet to learn and to accept or reject the principles of the Gospel
(James E. Talmage, The Articles of Faith, p. 58)