Why did the American colonies represent a safe haven for religious groups willing to move to a new place in the 17th and 18th centuries?

The American colonies were a safe place for the migration of smaller religious groups during the 17th and 18th centuries. In Europe, the Catholic Church was still strong, though it was on a decline gradually, and the religious problems in Europe were between the Catholics and every other smaller Christian branch. In the American colonies though, the Catholic Church didn't really had any political power. This meant that the people that had problems in Europe because of their religion were free to go to the American colonies, practice their religion, and have no worries of persecutions and conflicts. And so it was, numerous small religious groups moved into the American colonies, settled in places where there was still no European population, at least in most cases, and formed their own communities.