Poojya Swamiji enlightens us that there is a lot of science behind temples, installation of deity and deity worship. God is an all pervading presence, yet it is very difficult for most people to think or visualize his Omnipresence. So, the Priest who installs the idol, implores God to come and be present in the idol. He instills the force and power of Prana into the stone.
The air is present everywhere, yet we can only breathe it. It does not immediately help relieve us of the heat or sweating of the body. But when we use a handfan to blow the air, we get a sooting effect. The air becomes functional. In the same manner, when the idol is consecrated, people will have a focus there and will be able to come and pray to God by looking at the idol.
Shloka Chanted:
सर्वत्रगोഽसि भगवन् किल यद्यपि त्वां
आवाहयामि हि यथा व्यजनेन वायुम् |
गूढो यथैव दहनो मथनादुपैति
ह्यावाहितोഽपि हि तथा त्वमुपैषि चार्चाम्
sarvatragoഽsi bhagavan kila yadyapi tvāṃ
āvāhayāmi hi yathā vyajanena vāyum |
gūḍho yathaiva dahano mathanādupaiti
hyāvāhitoഽpi hi tathā tvamupaiṣi cārcām
Tantrasamuchayam 6.64