Hindus claim that they believe in "Eshwar" the one GOD, then why they have 360 million gods and worship idols.?

Hindus claim that they believe in "Eshwar" the one GOD, then why they have 360 million gods and worship idols. Is it not contradictory to their Original belief. I mean I don't know how one can worship a monkey or a rat or a (lung), or believe that one of their god lord krishna was a fornicator or adulterous. Look at Sikhs, they do not do that. How is that Hindus make statues with their own hand and then worship the same statue. May be I have ben away from India too long or may be I do not go to mandirs.