A person who forsakes religion:

Answer: Option C

The one word substitution is Renegade.

Apostle : a vigorous and pioneering advocate or supporter of a particular policy, idea, or cause.
Apotheosis : the highest point in the development of something; a culmination or climax.
Charlatan : a person falsely claiming to have a special knowledge or skill.
Renegade : having abandoned one's religious beliefs.