In first part of verse 12 (which we looked at yesterday), John encourages his readers to receive Jesus, that is, to believe in His name. To receive Jesus is to take Him at His word, to trust Him as Saviour and to turn from the darkness of this world, and the darkness in your life, and to submit to Him.
But receiving Jesus is not just a change in what we believe, it is a change of life and position. The rest of verse 12 says, “He give the right to become children of God.”
When you become a believer in the Lord Jesus, you become a child of God. This is something that we have become used to hearing, and we don’t feel the amazement that we should. Being a child of God is not something that we are naturally because of being human (remember verses 10-11 say that the world did not receive Him), nor is it something that happens because of our own power or decision.
Verse 13 makes this clear. Those who believe are children of God not because of natural birth or human effort or human decision but only because God Himself has worked in them. So, if you are a believer, you are a child of God, and the creator of the universe is your Father; He has adopted you, He has made you His, you belong to Him, you can talk to Him, you can rest in His care and love.
And you are child of God by grace alone, because God has given you new life; you are “born of God.”
What amazing grace! What an amazing God!