Hindu sculpture is characterized by the recurring holy symbols and invocation of the divine powers. Thus, one finds the use of OM, swastika, and lotus flower as the true symbols of auspiciousness and invocation of the divine consciousness.
Worshipping Hindu idols means that you close the door on demonic activities. However, the Sanatana Dharma focuses on two aspects of idol worship - the spiritual part and the cultural aspects. Even though the belief is that God is within you yet having an idol helps you to meditate more easily.