From his Bible Speaks Today commentary on Malachi, Peter Adam writes:
‘One of the frightening consequences of any sin is that it blinds us not only to the reality of specific sins we have committed but also to all sin. What great sins the people must have committed to make this response, How have you loved us? They are really saying, ‘Prove it’: challenging God to show them his love, and so negating all that God has done and said to them over past generations, and in their own experience…
What a frightening example of how sin blinds and binds, as we will know in our own lives and in the lives of our churches. For every time we sin, that sin makes us blind to its presence, less able to see it, and so more likely to repeat it. And sin binds, because every time we sin we weaken our power to resist sinning, and take the first steps in forming the habit of repeating that sin,’
Peter Adam, The Message of Malachi (BST), IVP, p37.