In both cases, lack of investigation would be cause. This is unbefitting the Christian especially. B. Lack of understanding 1. But they would not accept logical understanding that the scriptures forced them to reach about Jesus. C. Forgetfulness 1.
Forgetfulness translates into ignorance.
There's merit to that. This is why sermons are so necessary. A. Jeopardizes one's salvation - eternal life hangs in the balance. Consider some views of ignorance. These cause a person to be lost forever.