"Idol worship- Murti Puja"

Idol worship is worshiping a form. Although the idea that god is formless is ideal a normal mind cannot worship or think of an abstract concept. Worshiping is not about what God is but about what you can do naturally. Let's understand the three features of the mind.

1. Externalisation: The mind is always trying to run outwards. When you close your eyes and sit for meditation or desire concentration on one thought, one mantra, one image, the mind tries to run outside. So it is very natural for the mind to worship something that is outside.
2. Objectification: You cannot think of a pink elephant without creating an image of it in the mind. It is so natural that when you read or hear the word "ROSE" the mind creates an object that you understand as a rose. This happens to you so naturally. It is by nature that the mind needs an object.
3. Association: The mind cannot stay on one thought for long. The mind hops from one thought to the other. Even when you are concentrating on some God like Shri Rama your mind will divert. Now this diversification can be connected or completely disconnected to the central thought. In worshiping idol there is a beautiful concept of worshiping the "panchayatan". You must have observed that Shri Ram is not worshiped alone. He is always accompanied by Sita, Laxman, Hanuman and Shri Ganesh idols. So your mind may wander while thinking about Ram but not so far. Shri Vishnu shahastranaam is an excellent example of law of association. It is a poetic praise of Lord Vishnu, wherein the mind goes on from one aspect of shri vishnu to the other. And so is Hanuman Chalisa, Atharva shirsha, Ramraksha stotra, Shiv tandav stotra etc.

Moorti puja is a way to worship God by utilising the natural tendencies of the mind viz. Externalisation, objectification and asssociation. Once the mind gets trained to be internalised, abstract and dissociated a worshipper will no longer need the idols.