Commentaries:
One's blindness does not excuse his guilt. The person is still guilty even though he did not know.
Unintentionally, thankfully, includes more than one might think at first glance. It means "to turn aside, to wander, to err, to make a mistake, to miss the mark." The person misses the real objective in life, which is to obey God and to be holy as He is holy. It includes sins done with a degree of consciousness, that is, an awareness of what one is doing, as well as sins done willingly out of weakness, but not sins done deliberately.
For example, the Bible clearly differentiates between manslaughter and murder. Manslaughter is the taking of a life accidentally. There is no plan to do it—it just occurrs. The head flies off a hammer, hits somebody in the head, cracks his skull, and he dies. Nobody deliberately plans to do that, though there may be some carelessness involved in it.
Murder, however, includes a measure of deliberateness, lying in wait, planning, setting one's mind to do it. It may be a situation in which one burns in anger against someone for a period of time. Though he has plenty of time to bring himself under control, he does not. Then, reaching the boiling point, he murders his "enemy."
John W. Ritenbaugh
Examples of Divine Justice