As a librarian, I can tell this is a research question that may require additional resources if you're doing a project or paper. Check out your public library or school library and talk with a reference librarian. I will just offer a short summary.
The early colonists came to America to have a freedom to practice their religion of choice, which a freedom that they couldn't enjoy under European monarchies, particularly the British monarchy. This was so influential that freedom of religion is one of the 1st Amendment rights within the US Constitution. Freedom of speech, right to peacefully assemble, right to petition the government, and freedom of press are the other rights within the 1st Amendment. These rights also tie into protecting political choice within the new country. The US government cannot persecute people for its religious and political beliefs.