Physical birth brings you into the physical realm. Spiritual birth brings you in to God’s kingdom. 

“Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God”     John 1:13 (KJV)

Since we are born of God, we can survive by feeding on the word of God.

“But we will give ourselves continually to prayer, and to the ministry of the word” Acts 6:4(KJV)