Moses told the Israelites what God told him to say, that God would deliver them. But the Israelites did not listen. So when God told him to go talk to Pharaoh, Moses said, “The children of Israel have not heeded me. How then shall Pharaoh heed me, for I am of uncircumcised lips” (v. 12). The assumption here is that the effectiveness of the message depends on the how it is delivered. While I certainly believe that a messenger of God should take some care as to how he delivers the message, that is not ultimately the basis for effectiveness. In this case, the effectiveness of response depended on unparalleled mighty acts of God. The messenger’s priority is to take care that he accurately and obediently delivers the message, whether he has reason to expect a good response or not. He can be sure of this: if God has commanded a message to be delivered, he is at work. He has a plan to complete his own purposes. Just consider all the New Testament Scriptures in which God has called his people to speak (Matt 18:15-20; 28:18-20; Eph 4:15 . . .)