Lord Shiva is worshipped in the form of linga from ancient times. Lord Shiva is one of the trinity of Brahma, Vishnu and Mahesh and even considered to be supreme lord. He has been worshipped by various devtas (gods) in Hindu mythology and by Vishnu Dashavatara’s.
The Lingam symbolizes both the creative and destructive power of Lord Shiva and great sanctity is attached to it by the devotees. Mahadev is the only God who has both form “Sakaar Roop” who we can see and pray and also “Nirakaar Roop” like Shivling.
Puranas and scriptures in Hinduism narrate in detail why Lord Shiva is worshipped in the form of Linga. It is said that the he appeared before Lord Brahma and Vishnu in the form of a ‘pillar of fire’, which had no end and beginning. It is one among the many symbols of Brahman.
Incarnations of Lord Vishnu is known to have worshipped the Shivlinga including Lord Ram, Parashuram and Krishna.
When the mind is clear and is without prejudice, we will realize that the Linga form of Shiva is the most innocent form of Brahman that our ancestors had realized. It is pure and they got it from pure nature. Many of the forms that we worship today are the reflections of our mind, which is corrupted by ego, society and education. It is not pure.
As per the epic Mahabharata, ‘Know everything, which is male, to be Ishana, and all that is female to be Uma; for this whole world, animate and inanimate, is pervaded by these two bodies. Shiva’s divine Linga is worshipped by the Gods, seers, Gandharvas and Apsaras.’ (Chapter 7, section 20, verse 22)
Shiv Purana definition of Shivlinga
The Shiva Purana describes the origin of the Lingam, known as Shivalinga, as the one which has no beginning and no end. This is a cosmic pillar (Stambha) of fire, the cause of all causes.
Lord Shiva is pictured as emerging from the lingam – the cosmic pillar of fire – proving his superiority over the gods Brahma and Vishnu. This is known as Lingodbhava.
The Linga Purana also supports this interpretation of lingam as a cosmic pillar, symbolizing the infinite nature of Shiva.
According to the Linga Purana, the lingam is a complete symbolic representation of the formless Universe Bearer – the oval-shaped stone is the symbol of the Universe, and the bottom base represents the Supreme Power that holds the entire Universe in it.
Skanda Purana
“The endless sky (that great void which contains the entire universe) is the Linga, the Earth is its base. At the end of time the entire universe and all the Gods finally merge in the Linga itself.