The Jews who were in discussion with Jesus must have been beside themselves with anger. When they shouted, ‘We are not illegitimate children, the only Father we have is God Himself!’ (:41), they used the very words for which they shortly before had wanted to stone Jesus, ‘for He was even calling God His own Father’ (5:18).
Jesus spoke to the Jews who had believed Him (:31). In this passage it becomes quite clear that not everyone who believes Jesus is therefore instantly a child of God. After all, even the demons believe that — and shudder (James 2:19). God sent His Son in this world so that the world would believe in Him. But not like the demons!
In this conversation, Jesus clearly distinguished between descendants of Abraham and children of Abraham. We all are descendants of pious people, like Noah and Enoch, and God looks down on all people in mercy: ‘You are my sheep, and I am your God.’
Truly believing in Him means: completely trusting Him. Who really believes in Him, follows Him in all aspects of life. The children of Abraham do the works of Abraham (:39) and likewise the children of God do the works of God. Therefore Jesus told His followers, ‘Very truly I tell you, whoever believes in me will do the works I have been doing’ (John 14:12a). To His listeners, He said, ‘You are doing the works of your own father’ (:41), and a little later, ‘you want to carry out your father’s desires.’ He then stated frankly, ‘You belong to your father, the devil!’ (:44).
Many Christians do not realize that only through faith in the fulfilled work of Jesus on Golgotha and through obedience to God, we can change from creatures of God into His children.