John 15:11 I have told you this so that my joy may be in you and that your joy may be complete.
Jesus continued to give the disciples the truth from God and how much God was in control of everything.
All the words He gave to the disciples, and hence to us, are from God to show us His love for us; this is the gospel story which we have to continue to pass on to others.
He did not give us these words as propaganda or for other strange reasons; just simply so we can know how much He loves us and can live with that hope and truth every day.