Complex sentence: However, the researcher Ziauddin Lahori, the author of seven books on Sir Syed, believes that it is incorrect to say that Sir Syed propounded the two-nation theory.
Split into simpler sentences: However, the researcher Ziauddin Lahori, the author of seven books on Sir Syed, thinks otherwise. According to him, it is incorrect to say that Sir Syed propounded the two-nation theory.