Complex sentence: Mirza Ghulam Ahmad, the founder of Ahmadiyya sect of Islam, writes that he was the Kalki Avatar, the last avatar of Vishnu whom Hindus were waiting for.
Split into simpler sentences: Mirza Ghulam Ahmad, the founder of Ahmadiyya, a sect of Islam. Ahmad writes that he was the Kalki Avatar, the last avatar of Vishnu whom Hindus were waiting for.