CC Madhya 17.184
sabe ‘eka’-mata nahe, bhinna bhinna dharma
Śrī Caitanya Mahāprabhu replied, “The Vedas, Purāṇas and great learned sages are not always in agreement with one another. Consequently there are different religious principles.
Unless one comes to the Absolute Truth, there is no possibility of agreement. Nāsāv ṛṣir yasya mataṁ na bhinnam: it is said that a great learned scholar or sage cannot be exalted unless he disagrees with other scholars and sages. On the material platform, there is no possibility of agreement; therefore there are different kinds of religious systems. But the Absolute Truth is one, and when one is situated in the Absolute Truth, there is no disagreement. On that absolute platform the Supreme Personality of Godhead is worshipable. As stated in the Bhagavad-gītā (18.55), bhaktyā mām abhijānāti yāvān yaś cāsmi tattvataḥ. On the absolute platform, the worshipful Deity is one, and the process of worship is also one. That process is bhakti.
There are many different religions throughout the world because they are not all on the absolute platform of devotional service. As confirmed in the Bhagavad-gītā (18.66): sarva-dharmān parityajya mām ekaṁ śaraṇaṁ vraja. The word ekam means “one,” Kṛṣṇa. On this platform, there are no different religious systems. According to Śrīmad-Bhāgavatam (1.1.2), dharmaḥ projjhita-kaitavo ’tra. On the material platform, religious systems are different. Śrīmad-Bhāgavatam describes them from the very beginning as dharmaḥ kaitavaḥ, cheating religions. None of these religions is actually genuine. The genuine religious system is that which enables one to become a lover of the Supreme Personality of Godhead. In the words of Śrīmad-Bhāgavatam (1.2.6):
ahaituky apratihatā yayātmā suprasīdati
“The supreme occupation [dharma] for all humanity is that by which men can attain to loving devotional service unto the transcendent Lord. Such devotional service must be unmotivated and uninterrupted in order to completely satisfy the self.”
On this platform there is nothing but the service of the Lord. When a person has no ulterior motive, there is certainly oneness and agreement of principles. Since everyone has a different body and mind, different types of religions are needed. But when one is situated on the spiritual platform, there are no bodily and mental differences. Consequently on the absolute platform there is oneness in religion.