Knowledge Of The Lord - Isaiah 11:8-9

Isaiah 11:8-9 ESV 

The nursing child shall play over the hole of the cobra,

and the weaned child shall put his hand on the adder's den.

They shall not hurt or destroy

in all my holy mountain;

for the earth shall be full of the knowledge of the Lord

as the waters cover the sea.

One must become like a child to inherit the kingdom of heaven. This can be understood as the Holy mountain of the Lord. 

The knowledge of the Lord will cover the earth. It will guard and protect against those who have opposed God and His children. 

Where once the the waters of the deep darkened the earth, now the knowledge of the Lord brings light into the world.