The significance of the Number 18 cascades to several predominantly important features of Hinduism.
Sabarimala is engulfed in the predominance of the number 18.
It is believed that there are 18 steps to attain Moksha.
There are many theories about the significance of 18 steps in the pilgrimage to Sabarimala. It is believed that the steps represent 18 mountains surrounding the temple. On each step, the deity of the corresponding mountain has been installed. So when the devotee climbs the 18 steps to reach the sanctum sanctorum, he attains the punya of visiting all 18 hill gods. During the padipuja, deities of these 18 mountains are propitiated.
The 18 mountains are: Ponnambalamedu, Gowdenmala, Nagamala, Sundaramala, Chittambalamala, Khalgimala, Mathangamala, Myladummala, Sreepadamala, Devarmala, Nilakkalmala, Thalapparamala, Neelimala, Karimala, Puthuserrymala, Kalakettimala, Inchipparamala and Sabarimala.
The 18 steps are also considered as:-
5 indriyaas _ eye, ear, nose, tongue and skin;
8 rajas, kama, krodha, lobha, moha, mada, matasraya, aham and asooya;
3 gunas: satva guna, raja guna and tamo guna;
and vidya and avidya, thus making it 18.
Similarly, 18 is considered as the code number to break into the soul of the Nature. The significance of 18 can be traced back to the Vedic age.The first Veda, believed to be protected by Lord Brahma himself, had 18 chapters. Later, Veda Vyasa divided it to create the four vedas: Rigveda, Yajur Veda, Sama Veda and Atharava Veda.
Each of these vedas had 18 chapters.
Veda Vyasa also wrote 18 puranas and 18 upa-puranas.
The number 18 predominates the Mahabharatha Epic. It is written in 18 parvas or books.
Adi Parva, Sabha Parva, Vana Parva, Virata Parva, Udyoga Parva, Bhisma Parva, Drona Parva, Karna Parva, Shalya Parva, Sauptika Parva, Stri Parva, Shanti Parva, Anushasana Parva, Ashwamedhika Parva, Ashramavasika Parva, Mausala Parva, Mahaprasthanika Parva, Svargarohana Parva.
One more Chapter, Harivamsa Parva is added to the Epic as an addendum to the 18 books, and covers those parts of the life of Lord Krishna which is not covered in the 18 parvas of the Mahabharata
The Bhagavad Gita has 18 chapters and the Kurukshetra war lasted 18 days. 18 groups of soldiers were involved – 11 in the Kouravas side and 7 in the Pandavas. The War lasted 18 days.