How did Sai Baba's words affect the man who was initially against idol worship?

The effect was profound and immediate. As the man, who was Kaka Mahajani's friend, set foot on the step of the mosque, Baba called out to him. According to the account in Chapter 35, the magical power was in the tone of Baba's voice, which was a perfect imitation of the friend's deceased father. Hearing speech as if from his own father's mouth caused the friend to be utterly amazed and melt inside. This powerful, personal connection shattered his skepticism and preconceived notions, leading him to forget his resolve and bow down at Baba's feet.