Why could the disciples not have been preaching the finished work of the cross before Jesus died?
They could not preach the finished work of the cross because it had not yet been accomplished. Jesus had not yet died. In Luke 9, He told the twelve He would be delivered into men's hands, but they did not understand; it was hidden from them, and they feared to ask Him.
Les explains that the basic doctrine of salvation is by faith and faith alone in the finished work of the cross, but the finished work of the cross had not yet been accomplished when Jesus was with the twelve. So how could they be preaching something that hadn't happened? They didn't. He then points to Luke 9, shortly before the crucifixion and near the end of the three years, where Jesus said the Son of Man would be delivered into the hands of men. The twelve, however, understood not that saying; it was hid from them, they perceived it not, and they feared to ask Him about it. They could not even ask what He meant, let alone preach a completed cross. Les also plans to look at a series of verses in Luke 18.
More Questions
Why didn't the disciples preach the finished work of the cross before Jesus died?
The finished work of the cross had not yet been accomplished, so the disciples could not be preaching it; they did not preach it.