The image of Durga as Mahishasuramardini epitomizes the Chandi. To understand the significance of the image we have to understand the significance of the Chandi.
The gory scene depicted by the image of Durga, and the blood-curdling descriptions of a warrior Goddess exterminating hordes of evil doers drenching the earth with blood, may be enigmatic and repulsive to some people, especially to those who are outside the Shakta tradition of Hinduism. A mature and realistic understanding of the Divine in the context of the real situations in human life and society is necessary to understand the true significance of Chandi. The basic significance of Chandi may be briefly stated as follows.
The main purpose of Chandi is to glorify Shakti. Shakti is the dynamic aspect of the ultimate Reality known as Brahman. Shakti is generally regarded as the feminine principle. The feminine principle has two aspects: a lower, seductive aspect, and a higher, maternal aspect. It is the higher maternal aspect that is glorified in the Chandi, and in the Shakta tradition in general. Sri Ramakrishna used to say: Jini Brahma tini Shakti, tini i Ma ''He who is Brahman is Shakti, and He himself is the Mother of the Universe''
A mother has three main functions: to give birth, to nourish, to care and protect. It is the third aspect that is highlighted in the Chandi. God is not a disinterested spectator of the drama of human life. She is an active participant. She protects people from dangers. Think of the cosmic figure of a Divine Mother towering over millions of people guarding them from dangers, punishing evil doers. Well, you can see this image of the Cosmic Mother in the Chandi.