Funny title. What I mean by did Jesus change God is we have a sense that the God of the Old Testament is tough and the God of the New Testament is soft. I think we need to look closer and think more.
This is a big topic, but let me take it on. In Levitucus 10, We have the following.
The Death of Nadab and Abihu
10 Aaron’s sons Nadab and Abihu took their censers, put fire in them and added incense; and they offered unauthorized fire before the Lord, contrary to his command. 2 So fire came out from the presence of the Lord and consumed them, and they died before the Lord.
In Acts 5 we have:
“How could you conspire to test the Spirit of the Lord? Listen! The feet of the men who buried your husband are at the door, and they will carry you out also.”
10 At that moment she fell down at his feet and died. Then the young men came in and, finding her dead, carried her out and buried her beside her husband. 11 Great fear seized the whole church and all who heard about these events.
What is similar about the context of these two passages? I believe school teachers can understand.
To gain control of a class, teachers start the year very strict. Then, when they have established the boundaries, they start to back off. When the eternal life of humanity is at stake, God will establish enough boundaries.
So, in the Old Testament, God is often at the starting point with us. He establishes his attitude with the new king and trains the newly freed Hebrew slaves more.
We do well to remember God’s attitude toward unbelief, rebellion, lying, and failing to obey though He does n0t rain fire these days.
Did Jesus Change God? No, He Made Him Known
However, back to my point.
Note in the Sermon on the Mount, Jesus made the Old Testament laws harder by saying lusting or anger are like adultery and murder. How is this being softer? God is not like us and changing. He is our faithful God who always loves us and raises us to be mature children.
It is true that Jesus helps us to know God so much more by becoming a man and living among us. Nonetheless, he made living cultures but does not change with them. His values and what makes Him smile and frown have not changed.
In the Old Testament, God worked through the Israelites to prepare us for the coming of Jesus. Now, he is not working through a particular nation, but reaches out in love to people of all nations.
He blessed us by saying that we need new wine skins for new wine, so Christians learned to be flexible to portray God in each culture and each era. We should not, however, forget what God asks of us and how we should love the lost who do not know His ways. We should not push non believers to be moral, but rather love them where they are and invite them into a kingdom of love where God himself will teach them His ways.