The settlement was attacked from both sides for forty five years. Rome moved late and then decisively: in 1570 Pius V issued Regnans in Excelsis, excommunicating Elizabeth and declaring her subjects released from their allegiance, which turned every English Catholic into a potential traitor whether or not any of them wished to be. Priests trained in seminaries abroad began arriving in the 1570s, legislation made their presence itself treasonable, and executions followed, among them Edmund Campion in 1581. The state maintained that it punished treason and not religion. The condemned maintained the opposite. Both were partly right and the argument has never closed.
The other pressure came from inside. Clergy who wanted the church reformed further objected first to vestments, then to the prayer book, then to bishops. Archbishop Grindal was sequestered for refusing to suppress the preaching exercises called prophesyings; the Admonition to Parliament of 1572 demanded a presbyterian order; Whitgift enforced subscription; a small separatist wing gave up on the national church altogether. Elizabeth is reported to have said that she had no wish to make windows into men's souls, and the settlement worked largely by not asking, which satisfied nobody and held.