Moses, even after God talked to him; even after believing, and going to Pharoah; still questions and doesn’t think he is worthy; and still questions God. He is from the lineage of Reuben, Simeon and Levi (later the high priests). Being from these, houses he uses to call his lips uncircumcised. If you will remember, Reuben slept with his father’s concubine. Simeon and Levi both went and slaughtered a village because their sister was violated, threatening the safety of their whole clan. Does God want perfect people? If he did we would all be unusable. If He waited for us to all get ourselves together, nothing would happen. But God does these things, he uses those we deem the most unusable, so that HE can be the obvious recipient of the glory. If we were able, we would take the glory and lift ourselves up as gods. So let yourself be used, as broken as you are. He wants you, he wants you to let Him use you. Allow the Potter to mold you into the vessel He wants to use - and then watch the magic happen!