 Having been brought up in the Lutheran faith, he nevertheless questioned its teachings, something which became a burning issue when confronted with Roman Catholicism while studying in Florence.After making comparative theological studies, including reading the Church Fathers and by using his natural observational skills, he decided that Catholicism, rather than Lutheranism, provided more sustenance for his constant inquisitiveness.In 1667, Steno converted to Catholicism on All Souls' Day when Lavinia Cenami Arnolfini, a noblewoman of Lucca, insisted.