Another important point mentioned in this connection is anindaya -- we should not criticize others' methods of religion. There are different types of religious systems operating under different qualities of material nature. Those operating in the modes of ignorance and passion cannot be as perfect as that system in the mode of goodness. In Bhagavad-gita everything has been divided into three qualitative divisions; therefore religious systems are similarly categorized. When people are mostly under the modes of passion and ignorance, their system of religion will be of the same quality. A devotee, instead of criticizing such systems, will encourage the followers to stick to their principles so that gradually they can come to the platform of religion in goodness. Simply by criticizing them, a devotee's mind will be agitated. Thus a devotee should tolerate and learn to stop agitation. (SB 4.22.24 Purport)

Conversation with Father Emmanuel and Cardinal Danielou