Cuban President Raúl Castro paid a call Sunday on Pope Francis at the Vatican to thank him for working for Cuban-U.S. detente and said he was so impressed by the pontiff that he is considering a return to the Catholic Church’s fold.

“Bienvenido!” Francis said in his native Spanish, welcoming Castro to his studio near the Vatican public audience hall. The private meeting lasted nearly an hour. Francis will visit Cuba in September en route to the United States.

After leaving the Vatican, Castro, the brother of Fidel, the revolutionary leader who brought the Communists to power in Cuba, praised Francis. The pontiff “is a Jesuit, and I, in some way, am too,” Castro said at a news conference. “I always studied at Jesuit schools.”

“When the pope goes to Cuba in September, I promise to go to all his Masses, and with satisfaction,” he said at a news conference at the office of Italian Prime Minister Matteo Renzi, with whom he met after the Vatican talks.

“I read all the speeches of the pope, his commentaries, and if the pope continues this way, I will go back to praying and go back to the church, and I’m not joking,” he said.

It was a startling assertion for the leader of a communist country, whose crackdown on dissidents in the past had drawn sharp Vatican criticism.

“I am from the Cuban Communist Party, that doesn’t allow [religious] believers, but now we are allowing it. It’s an important step,” Castro said.

Speaking about Francis, Castro said he has been “very impressed by his wisdom, his modesty and all his virtues that we know he has.”

Castro had already publicly thanked Francis for helping to bring Havana and Washington closer together after decades of U.S. government policy of strict isolation of Cuba. On Sunday, he stepped up his praise on Francis’s push for the two nations to put enmity aside and work for reconciliation for the benefit of Americans and Cubans.

As he took his leave from the Vatican, Castro told journalists, “I thanked the pope for what he did.”

Francis gave Castro a medal depicting St. Martin of Tours, known for caring for the destitute.

The Vatican’s general policy of opposing economic sanctions as a foreign policy tool carries appeal for Cuban leaders and people, who have spent decades under a U.S. embargo.

After a meeting with Pope Francis, Cuban President Raúl Castro said that “if the pope continues this way, I will go back to praying and go back to the church, and I’m not joking.” (L'Osservatore Romano/AP)