What is Gohonzon? How it differ with an Idol?
The Gohonzon (The Object of Worship) of HBS
In other sects of Buddhism, statues or pictures of buddhas and bodhisattvas are usually adored as the object of worship. On the other hand, HBS adores Namu Myoho Renge Kyo, the sacred seven characters as the sole sublime Sacred Object (Gohonzon).
Nissen Shonin explaines the reason for this
However, this was not Nissen Shonin's own discretion. He just followed Nichiren Shonin's instructions. Nichiren Shonin considered that among the sutras which were taught by Shakamuni Buddha, the Lotus Sutra is the most important sutra. Because the Lotus Sutra contains the essence of all of Shakamuni Buddha's teachings and it unified and incorporated the sutras of others in which Buddhas, Bodhisattvas and the guardian kings of heaven appear and elaborated on its teaching.
Nichiren Shonin stated in his writing "Kanjin Honzon Sho" what the Gohonzon's aspect should be.
So far as the spectacle of the Sacred Object (Myohorengekyo) is concerned, it was situated in the center of the jeweled stupa floating in the sky above the Saha world, the land of the Primordial Buddha. Inside the stupa, on both sides of the Myohorengekyo, the Buddha Sakamuni and the Buddha Prabhutaratna (Taho) were seated. The main attendants of the Buddha Sakamuni were the four bodhisattvas, led by Visistacaritra (Jyogyo), while Manjusri, Maitreya and other bodhisattvas were seated below as attendants of the four Bodhisattvas.
The great or small bodhisattvas, who had been converted by the manifestations of the Buddha or who had come from other worlds were there looking up at the above mentioned great Buddhas and Bodhisattvas like ordinary people looking up at nobles in court. The Buddhas from the ten directions were seated on the ground, not in the sky; they were showing that they were as manifestations of the eternal Buddha representing their manifested lands.
So, in the Gohonzon Mandala composed by Nichiren Shonin, the Odaimoku, Namu Myoho Renge Kyo, the Fine Dharma enlightened by the Eternal Buddha, is written in the center of the Mandala, and on the right side and left side of the Odaimoku, the names of Shakamuni Buddha and Taho Buddha, bodhisattvas and the guardian kings in heaven are written in order.
An allegory is given below for clarification.
The Odaimoku in the Gohonzon is like a large tree. Buddhas, bodhisattvas, and others are the many parts that comprise this tree like the branches and leaves. So there is no need to display the icons of them in front of the Gohonzon. To display icons of them in front of Gohonzon is like breaking off the branches and harming the tree.