What is the benefit of inviting the common people and the disbelievers if they are excused for their ignorance? And is a person excused for their ignorance in general, or with conditions?

Excuse due to ignorance varies according to individuals, circumstances, and issues. Not all ignorance renders its possessor excused, for any ignorance that a legally responsible person can dispel does not constitute an excuse for him. There is a difference between ignorance and forgetfulness; forgetfulness assails a person coercively, whereas ignorance can be dispelled by learning. A legally responsible person is not permitted to undertake an action until he knows Allah's ruling on it, and whoever falls short in acquiring obligatory knowledge will be held accountable for his ignorance.

Some scholars believe in the possibility of excusing for ignorance while still faulting the negligence in seeking obligatory knowledge, as Umar did with the Nubian woman who was ignorant of the prohibition of fornication. He flogged her as a disciplinary measure for her negligence in learning, but he did not apply the hadd punishment due to her ignorance.

Excuse due to ignorance means lifting sin or disbelief, or not requiring قضDaa (making up for missed obligations), and it does not mean that the ignorant person is equal to the knowledgeable one who follows the truth, nor does it imply abandoning calling people to Islam and teaching them.