Context: Following the 1660 restoration of royal rule in England, it was necessary to gain a Royal Charter from King Charles II. Charles was a Catholic sympathizer in staunchly Protestant England, and he approved of the colony's promise of religious freedom. He granted the request with the Royal Charter of 1663, uniting the four settlements together into the Colony of Rhode Island and Providence Plantations. In the following years, many persecuted groups settled in the colony, notably Quakers and Jews. The Rhode Island colony was very progressive for the time, passing laws abolishing witchcraft trials, imprisonment for debt, most capital punishment and, on May 18, 1652, chattel slavery of both blacks and whites.

Question: what was the purpose of rhode island colony?
Steam of consciousness below:

To answer this question, we should know that: Charles was a Catholic sympathizer in staunchly Protestant England, and he approved of the colony's promise of religious freedom.
So, the answer is religious freedom.