Question: In the Nectar Of Instruction, Srila Prabhupada said that devotional service is ahaitukiapratihata. Bhakti is not affected by any mundane cause or curtailed by any material interruption. My question is, how do sinful activities slow one’s progress in devotional life?

Jayapataka Swami: Srimad Bhagavatam 1.2.6 Translation:  The supreme occupation [dharma] for all humanity is that by which men can attain to loving devotional service unto the transcendental Lord. Such devotional service must be unmotivated and uninterrupted to completely satisfy the self.
The question was, what sinful life has to do with this? Obviously, the sinful activities are interruptions to our bhakti. And therefore, the pure bhakti is satisfying to the self, but if they are interrupted by sin, they will not be satisfying to the self. Therefore, the four pillars of irreligiosity are forbidden.
28-Nov-2020 ŚRĪ MĀYĀPUR DHAM, INDIA