This shirt features the Keys of Saint Peter, used as the Papal Crest.
"Jesus said to him in reply, “Blessed are you, Simon son of Jonah. For flesh and blood has not revealed this to you, but my heavenly Father. And so I say to you, you are Peter, and upon this rock I will build my church, and the gates of the netherworld shall not prevail against it. l I will give you the keys to the kingdom of heaven."