Ending up in Geneva, Bruno joined the Calvinist Church, but he soon discovered that this was no more tolerant of free thinkers than was the Roman Catholic Church. Arrested in Geneva, he found himself excommunicated from the Calvinist Church but after retracting he was allowed back into the that Church and was then free to leave Geneva.
Nagtatapos nang hanggang sa Geneva, Bruno sumali sa kalvinista Iglesia, ngunit siya sa lalong madaling panahon natuklasan na ito ay hindi maaano ng libreng thinkers kaysa noon ay ang Simbahang Katoliko Romano. Inaresto sa Geneva, siya natagpuan ang kanyang sarili eskolmulgado mula sa kalvinista ngunit Simbahan matapos retracting siya ay pinahihintulutan sa likod na Iglesia at pagkatapos ay libre upang umalis sa Geneva.