This photo was a response (thanks to Ignatius Insight) to the anti-religious advertisement campaign developed in London, with ads reading “There’s probably no God. Now stop worrying and enjoy your life.”
It is taken for granted, of course, by the original ad, that the existence of God is a cause for worry rather than peace and happiness. A propos of this, see these reflections on Paul’s teaching on predestination as a cause of joy in St. Paul.