Reason for born again
To be born again means to have part in the kingdom of God and also partake in Godly nature, which we need to struggle to become like God so that we can restore our original nature that God created us into.
God did not create this world to be empty but created to be inhabited by man and He gave man dominion over this Earth. It means that man should be the caretaker of what God has created. Satan saw that man is going to be in charge of all the creation of God. Then Satan devices a plan to rob man the dominion thereby make man to loss this estate.