“Yet to all who received him, to those who believed in his name, he gave the right to become children of God—children born not of natural descent, nor of human decision or a husband’s will, but born of God.” John 1:12-13
This is a reason that Jesus came to earth, so that we might become children of God. Each one of us is born with a sin nature, one that separates us from God and drives us to rebel further against Him. This nature needs to be put to death, and a new nature given.
The coming of Christ accomplishes exactly this. He has put sin to death on the cross and clothed us with a new nature. He has restored our relationship with God the Father who adopts us as His children making us co-heirs with Christ.