Fred from South Carolina asks, “Moses describes himself as ‘slow of speech and and of tongue,’ but Moses was highly educated and eloquent, so does this mean that Moses was unable to speak?”
In Exodus 4, Moses gives five different excuses to God, each one indicating that he should not be the person sent to Pharaoh. This particular excuse about his speech is the fourth in the list. So keep in mind that Moses was greatly exaggerating his own weaknesses as he attempted to convince God that he was not the right person. And, of course, God saw right through his exaggerations and excuses.
But taking Moses’ words as true, there are two different interpretations of what Moses means when he says “slow of speech and tongue.” Some scholars believe that Moses has some speech impediment, or stammer, that affected him as he spoke in public.
This is a possible explanation, but it would seemingly contradict Stephen, the New Testament believer who said this of Moses as he spoke to the Jews before being stoned to death: “He was mighty in his words and deeds” (Acts 7:22). And it's true that the Pentateuch is filled with long and eloquent speeches Moses delivers to Israel.
I believe the most likely explanation for this verse is that Moses did not believe he had a strong enough grasp of Hebrew or Egyptian to speak before Pharaoh. This was an issue of eloquence and vocabulary and grammar in the mind of Moses.
He felt inadequate to make his case and answer any questions or objections, much like a person today might be able to order food with the Spanish they learned in high school, but would have a much harder time engaging in a complex theological discussion with a native Spanish-speaker.
But remember: this story is not a story of Moses’ insufficiency, but of God’s sovereign sufficiency. God did not need Moses to bring any skills, talents, or value to His plan. God was going to give Moses exactly what he needed to fulfill His purposes. And God does the same with us every day. Your limitations mean nothing to God; He has already prepared you for the purposes He has for you in His divine plan.