Answer: Based on its prefix and use in this context, the word immutable most likely means "that does not change over time".
Step-by-step explanation: The word "immutable" contains the prefix "im-", whose meaning is "not". When "Im-" is attached to a root word, the prefix changes the meaning of the root word by negating it. In that way, "immutable" is used to describe something or someone as unchanging, that is to say as a thing or person that does not change with the passing of time. Moreover, there are certain context clues in the passage that help the reader to figure out the meaning of "immutable" such as "eternal", "infinite" and "perfections".