The most significant threat that Mary posed to Elizabeth, was the threat of her accession. She had an unimpeachable entitlement to the throne; her marriage to Darnley made this even stronger. Elizabeth had no heir, and she refused to name one – this led to an unsettled accession and strengthened Mary’s position as a successor. To further complicate matters, according to Catholics, Elizabeth was illegitimate; they did not recognize the marriage of her mother (Anne Boleyn) to her father, as his divorce to his previous wife had been turned down by the Pope. Thus, it was believed that Elizabeth’s status and place in the social hierarchy was unlawful. Despite being restored to the line of succession under the Act of Succession in July 1543 many – including foreign powers- still saw her as the illegitimate daughter of an unlawful marriage. Furthermore, Elizabeth had converted England’s official religion to Protestantism, leaving many Catholics dissatisfied. Mary was a Catholic and many viewed her as their figurehead and a equitable replacement to the throne- Catholic supremacies in Europe hoped that Mary would become queen of England, either at Elizabeth’s death or through a Catholic rebellion. It was believed Catholics abroad or in England might seek to implement Mary’s claim and as such was seen as the origin of the Catholic threat. There were still many Catholics living in England during Elizabeth’s reign; devoted Protestants were still only a small minority. Various plots centered on overthrowing Elizabeth and putting Mary on the throne, and acted as a peril to Elizabeth’s reign.Despite the idea that Mary looked to be a suitable replacement for Elizabeth, she arrived in England with considerable baggage from a civil war with her nobles, and the suggestion that she had been implicated in the murder of her last husband. Additionally, Mary was not likely to gain the support simply due to the fact that she was involved in scandals and was extremely discredited. She was unequivocally hated in Scotland. She had been excluded from the throne by Henry VIII making any possible accession more unlikely. Elizabeth felt drawn to her as a relative, of which she had few, and as a fellow Queen but political considerations drove Elizabeth to keep Mary at arm’s length. To have embraced a controversial Catholic Queen as her cousin, Elizabeth would have risked angering Protestants- even if committed Protestants were only still a marginal amount in Elizabeth’s sovereignty. Once Elizabeth realized the Catholic nobility would not give up on their quest to enthrone Mary as Queen, the only option she had was to kill Mary.