In 1570, Pope Pius V issued the Papal Bull Regnans in Excelsis, which formally excommunicated Queen Elizabeth I of England. This act not only declared her a heretic but also released English Catholics from their allegiance to her, further intensifying the already existing persecution of Catholics in England. The excommunication heightened tensions between Catholic and Protestant factions in England and contributed to the broader geopolitical struggles of the time, particularly in relation to Spain and the Catholic Church.

The bull deepened the tension between Catholic and Protestant identity that pervades Elizabethan poetry; it made religious allegiance a matter of treason, driving Catholic verse underground and giving it a clandestine intensity, influencing poets like John Donne who navigated the complexities of faith.