The Vienna murder of a Ravidasi saint has two sides: historical background and Immediate reasons. (1)
Background: Guru Nanak, a Khatri by caste became saint in 1500 AD. He sang songs in praise of Hindu gods. He met two saints at Kashi, Guru Kabir and Guru Ravidas, who changed his course. He started singing bani (sermons) of these gurus. Some old scholars claim that Guru Kabir was his real guru. Anyhow he spread message of these gurus in Punjab. Nanak’s followers were called Sikhs i.e. learners. Sikhism had ten gurus. Early Sikhism is nothing but teachings of Guru Kabir and Guru Ravidas. It completely discarded Brahmins and their rituals.
Brahmins use Sikhs: The ninth Guru was approached by Brahmins. They flattered him and his son Guru Gobind Singh (10th and the last guru) But the 9th guru was beheaded at Chandni Chowk, Delhi.
Guru Gobind Singh (1699) started the Khalsa Panth. Mostly Mazahabis and Chamars joined his army. No
Brahmin came. Though it is true that the Sikh religion was born to fight Brahminism, the fact is the Brahmins throughout used the Sikh martial race to attack and kill the Muslims.
Despite M.K. Gandhi deceiving them on Sikh homeland and Jinnah promising the same, they did not join Pakistan but preferred to go with Brahmins. Even after the “Blue Star” massacre of Sikhs, they simply forgot all the crimes and joined the Brahmana Jati Party (BJP) as its electorate partner.
Though the Sikhs are not trusted by the Hindu rulers, they will be too eager to fight Pakistan if another war breaks out. To that extent they are hinduised (corrupted).
All the gurus treated Dalits with dignity. So too the Jat Sikhs. But after the death of Gobind Singh, Brahminic people (called Masand) took charge of Sikhism.
Dalit bani in guru Granth: This situation continued till the advent of Dr. Babasaheb Ambedkar. Many Chamars from Jallandhar area went abroad and became millionaire/billionaires. They promoted Ravidas mandirsigurudwaras. When Kanshi Ram, a Punjabi Dalit, started his movement, Dalits joined him fully.
Guru Nanak carried with him bani (writings) of Dalit gurus. He commanded his successors to compile bani is of all the saints. Almost all Dalit saints’ bani have been included in the Guru Granth. This bani is recited in all Sikh gurudwaras and also Ravidas mandirs called Dera
Some 5-6 years back, some Sikhs came to a dera and tried to hoist Nishan Sahib (a sword like symbol of Sikhs) to annex Ravidas temples under the Sikh Gurudwara Prabandhak Committee (SGPC). Dalits of all castes resisted and foiled the move. Bloody fights broke out between Jats and Dalits who showed their real strength. It is a historical fact that Dalit Sikh’s sacrificed their lives for Sikh gurus but the upper caste Sikhs always betrayed them. A peace pact was arranged between Dalits and Jats by then CM. Amrinder Singh, at Akal Takhat (the highest seal of Sikhs) which directed the SGPC not to meddle with deras.
Dera Sachkhand Ballan is the most popular Dera of Guru Ravdas. Two years ago its followers made an idol of pure gold worth crores of rupees, tock it thru procession from Punjab to Varanasi. Millions of Dalits joined the procession
This hurt the caste pride of upper caste Sikhs but they had no courage to touch the Ballan saints. So they chose Austria
However, the Chamars showed their courage and killed one/two gun-wielding attackers without any weapon.

