Because some American colonies allowed religious freedom and America was seen as the land of opportunity.
Explanation:
The history of Colonial England in the United States is of great irony: the same Protestant groups that fled England for tolerance and religious freedom brought with them an absolute hatred for the Church. They installed laws and customs that excluded Catholics from all aspects of public life for over a century and a half.
However, despite the growing hatred of Catholicism among the American colonies, some colonies, such as Maryland, established some religious freedom (with limitations on Catholics), which allowed some priests and nuns to settle in America, as America could bring many opportunities that would improve their lives.
Some English Catholics settled in Maryland. In 1789 the Archdiocese of Baltimore was the first diocese in the newly formed United States. John Carroll became the first American bishop.
Because B.C stands for Before Christ and A.D means the year of our lord so historians took a turn from the traditional christian time method and made it B.C.E (before common era) and C.E (common Era)
