Step 1: Identify the sociologists.
\begin{itemize}
\item Auguste Comte is known as the "Father of Sociology."
\item MacIver was a well-known sociologist who contributed to social theory.
\item G.S. Ghurye is regarded as the "Father of Indian Sociology."
\end{itemize}
Step 2: Identify the non-sociologist.
Charles Darwin was a natural scientist and biologist, famous for his theory of evolution. He did not work directly in sociology.
Step 3: Conclusion.
Thus, Darwin is not a sociologist.
Final Answer: \[ \boxed{\text{Darwin is not a sociologist.}} \]