God, who gave to our forefathers many different glimpses of the truth in the words of the prophets, has now, at the end of the present age, given us the truth in the Son. Heb. 1:1, Phillips.
What do you do when you read a text like this one: "But Moses said, 'O Lord, please send someone else to do it.' Then the Lord's anger burned against Moses" (Ex. 4:13, 14, N.I.V.). Then turning to Matthew 5:22, you read, "But I tell you that anyone who is angry with his brother will be subject to judgment" (N.I.V.).
A candid person will have to admit that it raises several questions. Why did God have to get burning angry against Moses when all he did was plead his feelings of inadequacy? Why does Jesus later warn us against becoming angry with other people? Are Jesus and God working from a different set of rules? Does God "get by" with certain behaviors that are against the rules for us, but allowed for Him since He is in charge? And since anger is so unproductive of good anyway, why does God have to express it against His friend Moses, especially when He has already sent Aaron along to speak in his place? There must be a better solution than to see a gentle Jesus in the New Testament and a short-tempered despot in the Old.
It is a mark in God's favor that He always speaks to His people in words and through meanings and experiences that make sense to them. You couldn't call it "communication" if He didn't. Certain idioms of thought and of interpretation make good sense to one culture but seem strange and puzzling to another. Each segment of the Bible was written in the context of a people and their familiar expressions.
Moses sensed that his courage was not yet up to doing all that God was eager for him to do. He felt the chagrin of knowing that because of his weakness God had had to resort to a backup plan to get the message to Pharaoh. It was not uncommon for the Hebrew mind to speak of God's feelings in very intense terms, thus speaking of His disappointment as burning anger. But we look in vain for any evidence of angry feelings or action in the paragraphs that follow.
God spoke His final words about Himself, however, when He sent His Son to be the "flawless expression of the nature of God" (Heb. 1:3. Phillips).