It is not at all compulsory to think divinity in the places where you find it difficult to imagine. But at the same time realize that there are others who find it most convenient to think divinity in idol. Every one has liberty to choose the way to achieve the aim. Here in India people find it most convenient to think that there is DIVINE GOD present in the idol. They think it is REAL Krishn and take his complete care as if that idol were a living being.
Better way is to imagine GOD is with you in the form according to your liking.
The theory of KARMA YOGA is “Senses in work, Mind with God”. This is theory of DEEDS. That is what Krishn tells Arjun in GEETA. “Think of me all the time and keep on doing your work.”
Although it looks like difficult, it can be achieved with constant practice