Once Srila Prabhupada was asked about the "oneness" of Brahma, Visnu, and Siva. He agreed that oneness existed, but that Visnu was nonetheless always superior. The exchange (during a Hyderabad lecture on Nov 25, 1972) went like this:
Audience man: ...that is omkara. Omkara-svarupa. But what I want to know is who is Lord Siva, Visnu and Brahma? Whether these three of them are gods?
Prabhupada: Yes. They're expansion of God. Just like the earth. And then, from earth, you find trees, wood. And then, in the tree, you can set fire. It becomes smoke. Then comes out the fire. When you get the fire, you can take your work from the fire. So the, everything is one, but... Just the same example: from earth, the wood; from wood, the smoke; from smoke, the fire. But if you have to take business, then it is required the fire, although the, all of them, are the one. Similarly, there are demigods, Brahma, Visnu, Mahesvara. So if you have to take business, then you have to go to the fire, Visnu, sattama, sattva-guna. This is the process. Although they are one, but your business can be completed with Visnu, not with others. What is my business?
My business is to get out of these material clutches. So if anyone is eager to be free from these material clutches, then he must take shelter of Visnu, not others.