The Ark of God was a symbol of the Lord God’s presentence with the people of Israel. The only thing in this chest-shaped artifact was two stone tablets that had the covenant between the Lord God and Israel carved into them. The people were to inquire of the Lord before the Ark.
David was the king of Israel. He moved to Jerusalem. He loved the Lord God and had inquired of the Lord God often through the high priest of God. He wanted to move the Ark to Jerusalem so the Lord would be close to him. A man of God desires to be with the Lord all the time.
While moving the Ark from Baalah of Judah (Kiriath Jearim) to Jerusalem a man who was not a priest touched the Ark and died 9, 10). He had good intentions. His intentions were not what killed him. Rather, the Lord gave Moses specific instructions on how the Ark was to be moved. David and the Israelites had not followed those instructions.
The Lord God is holy. He is to be honored and awed. He is due respect. David learned the hard way that fear of the Lord is the beginning of wisdom (12). He blesses though who honor him (14). He curses those who dishonor him. The fear of the Lord brings about obedience and blessing.