Why was the son so worried about his father, a Prarthana Samaj follower, taking over the daily worship of Sai Baba's photograph?

The son's apprehension stemmed from a difference in religious practices between him and his father. The son was a devout devotee who performed daily worship of Sai's photograph, including a food offering, without fail. Chapter 9 explicitly states that his father was a follower of the Prarthana Samaj, which presented a "great puzzle for the son." This suggests the father's beliefs might not align with idol worship. The son worried about how it would be right to entrust the "effort of idol worship" to him, fearing the ritual would not be performed with the required devotion and regularity, thus breaking the sacred routine he maintained.