Answer:
After the American Revolution, and the ratification of the Articles of Confederation, a feeling was left in the newly created United States that these Articles were a bit weak in certain points, particularly in regards to the power of the federal government, and thus needed a bit of amendment.
As such, and with a majority of leaders agreeing, in 1787 the Constitutional Convention was initiated and in it a new Constitution was signed and ratified. This new Constitution changed several points placed in the Articles, and empowered the federal government, particularly Congress.
But not everyone was happy with that federal empowerment and they pushed for a Bill of Rights with which they ensured that the federal government´s power, especially that given to Congress, would never surpass the rights of the people. These people who opposed this new Constitution, and pushed for the creation of the Bill of Rights, became known as the Anti-Federalists. Best known of all was Patrick Henry, the leader of the movement, and with him were figures of the level of Thomas Jefferson and Samuel Adams.
This text given on this question is definitely Anti-Federalist precisely because of that, because it insists on the dangers of placing so much power in the hands of a central government. So, for example, when the text says: "In giving such immense, such unlimited powers, was there no necessity of a Bill of Rights, to secure to their people their liberties?" you know you have an Anti-Federalist author because he is opposing centralized and powerful government without an assurance that individual rights are being protected from abuse.
