Here's a small story about Swami Vivekananda's ideology and importance of Idol Worship.
Once, Swami Vivekananda visited King of Alwar in present day Rajasthan. The king in an attempt to mock idol worship told Swamiji, "I've no faith in idol worship. How can one worship stone, wood and metal? I believe people are in illusion and just wasting time!�
Swamiji smiled. He asked the king's assistant to take down the picture of the king that was hanging on the wall. Although confused, the assistant did so. Then Swamiji ordered him, "Spit on the picture!� The assistant was shocked and looked at both of them. Swami repeated again and again, becoming sterner each time. The king was growing angry and the assistant started trembling. Finally, he cried out, "How can I spit on this? This picture is of our beloved and respected king!�
Swamiji then told him, "The king is sitting in front of you in person. This picture is merely a paper - it does not speak, hear, think or move. But still you did not spit because you see a shadow of your king in it; Spitting on it was like spitting on the king itself." The king looked at Swamiji and bowed down, clearly understanding what he was referring to.
This is the essence of idol worshiping. God is everywhere, but people want to pray to Him, offer food, tell stories, decorate him by using flowers and garlands and do what they do in their lives. Creating a human-like idol of God as a companion, a guide, a friend, a protector, a giver, a fellow being and so on. An idol is just a concrete representation where they find Him. When I look into the eyes of an idol, I do not see stone or metal, but another pair of eyes looking affectionately at me, smiling.