Moses kills a bunch of people in the name of God?

Participating in a Bible study this week and these verses came into the conversation:

25 When Moses saw that the people were running wild (for Aaron had let them run wild, to the derision of their enemies), 26 then Moses stood in the gate of the camp, and said, ‘Who is on the Lord’s side? Come to me!’ And all the sons of Levi gathered around him. 27 He said to them, ‘Thus says the Lord, the God of Israel, “Put your sword on your side, each of you! Go back and forth from gate to gate throughout the camp, and each of you kill your brother, your friend, and your neighbor.” 28 The sons of Levi did as Moses commanded, and about three thousand of the people fell on that day. 29 Moses said, ‘Today you have ordained yourselves for the service of the Lord, each one at the cost of a son or a brother, and so have brought a blessing on yourselves this day.’ 30 On the next day Moses said to the people, ‘You have sinned a great sin. But now I will go up to the Lord; perhaps I can make atonement for your sin.’ 31 So Moses returned to the Lord and said, ‘Alas, this people has sinned a great sin; they have made for themselves gods of gold. 32 But now, if you will only forgive their sin—but if not, blot me out of the book that you have written.’ 33 But the Lord said to Moses, ‘Whoever has sinned against me I will blot out of my book. 34 But now go, lead the people to the place about which I have spoken to you; see, my angel shall go in front of you. Nevertheless, when the day comes for punishment, I will punish them for their sin.’ 35 Then the Lord sent a plague on the people, because they made the calf—the one that Aaron made.

Kinda messed up. 

First off, it is worth noting in previous verses God wanted to destroy the people but then Moses talks God into changing God's mind. And so in verse 14 God changes God's mind and does not consume the people. 

But then you get Moses coming down the mountain and seeing all this "running wild" and gets those who are on "God's side" to kill those who are not on "God's side". Of course Moses commands all this under the declaration of "Thus says the Lord." Again, God just changed God's mind, God will not destroy the people. 

Could it be that this action, is the sin of Moses? Moses calls for a killing of people in order to purify the ranks and then tells the now 'pure' people, "Hey the sin we saw happen was rather big and we destroyed the people who were the problem. I will go up and talk with God to make an atonement and set all this right again. Just wait here." 

Moses goes up and says to God - please forgive us as we sat by and allowed this golden calf to be created. If you would not forgive us, then kill me as a way to appease your anger. 

God says - Moses, I will take care of those who sin against me in my own way (whatever it means to be blotted from the book), I will punish them through a plague. In case you forgot I said I did not want to destroy the people then you go down and kill all these people! What the heck are you doing?! This is not what I said and here you go putting my seal on your actions. I do not desire these people to die, but it seems you did.  


I know I am taking some artistic licence here, but I struggle with the idea that God says God will not destroy then Moses goes down and kills 3000 people in the name of God. Did Moses sin and kill a bunch of people in the name of God?