Who was Jesus speaking to when He gave His teachings?
Jesus gave His teachings primarily to people living under the Law—Israel under the Law. For example, when He cleansed lepers, He told them to show themselves to the priests. Since the death, burial, resurrection, and revelation of grace, believers no longer follow Christ after the flesh or the things He taught Israel under the Law.
Les explains that although everything Jesus said is the Word of God and can have application, for the most part His words were spoken to people living under the Law. He points to the healed lepers being told to show themselves to the priests as proof that Jesus' instructions fit that Law context. Les notes there is no temple worship today because we are not under the Law. To make this certain, God prompted the Roman Army to destroy the temple, uproot the priesthood, and send Israel out into the nations, removing any temptation to cling to temple worship. Paul therefore says that since the death, burial, resurrection, and revelation of the gospel of grace, we no longer know Christ after the flesh or go by the things He taught Israel under the Law.