The artist said he "found idle trains trips an amazingly fruitful time for prayer and contemplation". It's a non profit exercise and "just a little idea for those Circle Line passengers who believe that pondering on the enormous mystery of Christ’s death [and mysterious enormity of His love] could be a good thing".
Speaking to The Catholic Herald he said that a series of paper cut illustrations of Jianzhi pandas, given to him by his mother when he was eight, was his inspiration.
After exhibiting, the original illustrations may go up for sale with proceeds going to charity. If you're interesting in exhibiting, contact the artist here. Many thanks to Ianvisits who originally alerted me to these illustrations. They'd also look interesting alongside the Poems on the Underground ads on the Tube. For me they make a diverting alternative to variety of religious ads on the London Underground we can ponder or stare at on our journeys.