One day I was going to a funeral about two hours or so from where I was living.  I had the pleasure of travelling with my friend David Blevins.  I had a good idea.  'Let's redeem our time by teaching each other a verse from the Bible to memorise.'  David's favourite verse is Psalm 90:1 ('He who dwells in the shelter of the Most High will rest in the shadow of the Almighty').  The verse I chose as my favourite was 2 Corinthians 5:21 ('God made him who had no sin to be sin for us, so that in him we might become the righteousness of Christ').  This is called the doctrine of substitution, which explains that on the cross Jesus died as a substitute for us, taking the punishment that we deserved.  Listen to John MacAurthor as he claims that this concept, and this verse, is at the heart of the good news (the gospel).