Why did Moses not fully disclose to Jethro why he was leaving Midian? Why did God tell Moses to perform miraculous signs before Pharaoh when God also said he was going to harden Pharaoh's heart? Why was the Lord about to kill Moses shortly after he sent him on His mission? These are hard questions to answer, but they begin to make sense when we consider the theme of divine sonship- that God adopts us as His sons and daughters by grace, ultimately through His perfect Son, the Lord Jesus Christ.
We are all good at making excuses and raising objections when it comes to following the clear commands of God, but He deals patiently with us in His mercy through the grace of His Son who obeyed perfectly in our place.