Then the LORD said to him, “Who has made man’s mouth? Who makes him mute, or deaf, or seeing, or blind? Is it not I, the LORD? Now therefore go, and I will be with your mouth and teach you what you shall speak.” (Exodus 4:11–12, ESV)
God is sovereign over abilities and disabilities in all men, the devil does not afflict people with disability, God is the one who controls this. So we look to him.
God has made us and knows us, he knows the gifts and abilities he has given us, however we still need his help every step of the way which is why it was right for Moses to appeal for help in the traditional way with his ritual protest and over stated humility.
But he said, “Oh, my Lord, please send someone else.” (Exodus 4:13, ESV)
Moses probably gripped by fear is point blank refusing to heed the Lord’s call here, a bit like Jonah. We need to train our hearts to be courageous and say yes to the Lord
I appeared to Abraham, to Isaac, and to Jacob, as God Almighty, but by my name the LORD I did not make myself known to them. (Exodus 6:3, ESV)
God making himself known by his unique personal name YHWH signifies God opening himself up to true communication, availability and accessibility to Israel with whom he makes covenant based on this name (God’s names and titles revel to us who he is)
This name which is explained at the burning bush (I am who I am) is a name that can only be known through experience and walking with God in faith, this is what the Lord invites Moses ad the children of Israel to do
The next day he saw Jesus coming toward him, and said, “Behold, the Lamb of God, who takes away the sin of the world! (John 1:29, ESV)
This is what Jesus does, he takes away our sin