Alma 21:9

9 Now Aaron began to open the scriptures unto them concerning the coming of Christ, and also concerning the resurrection of the dead, and that there could be no redemption for mankind save it were through the death and sufferings of Christ, and the atonement of his blood.

Okay, so Aaron was going to add other witnesses (the prophets, who they (I suppose) are gathered in the synagogue to study) to his own testimony, and to their fathers'.

He is going to make it a little harder to disbelieve.

I wonder how hard/easy it is to reject truth when it stares you in the face, and you can feel it?

An important question for me to ponder.