O son of Kunti, even those devotees who worship other gods with faith, they too worship Me, but by the wrong method. (Bhagavad Gita Chapter 9 verse 23)
Any worship offered in good faith, no matter to which deity the worship is directed, goes to Bhagavan. Yet the ignorance in which the worship is offered prevents devotees from attaining the highest results, which is liberation. The nature of their ignorance is now shown.
For I alone am the Enjoyer and Lord of all sacrifices; but they know Me not in Truth and hence they fall (into rebirth). (Bhagavad Gita Chapter 9 verse 24)
Their ignorance consists in not realizing that in reality Bhagavan is the God to whom sacrifice is offered. It is in the form of the devata that Bhagavan is the Enjoyer of the sacrifice. And He is the inner Regulator of the universe, the Consciousness in the gods and also in the performer of the sacrifice. ‘They do not take refuge in Me; they are satisfied with what inferior gods can give them and they know not that even these inferior deities would be powerless if it were not for Me.’ That is why these devotees do not reach the highest but come back to earth.
By worshipping other gods they attain, no doubt, to the sphere of their sacrifice, but after the exhaustion of the results, they come back from there to the mortal world. That is all that they wish for and therefore that is all that they attain. The worship of inferior gods is not entirely useless, but it does not bring freedom. And again there are different grades even in this lower form of worship and so also in the results according to the degree of purity and understanding of the worshipper.