What is the relationship between Sikhism, Hinduism and Jainism in a doctrinal sense?
There is no word like ‘Hindu’ until recently. It was ‘Sanatana Dharma’, (the ancient religion). The practices and epics and vedas are evolved over thousands of years. Jainism and Sikhism were born out of Hinduism. Generally they pray in each other’s temples or Gurudwaras. Due to the extreme oppression of Hindus by Mughal emperors, Guru Nanak Dev started Sikhism by anointing the first son of a Hindu family as ‘Sikh’. The present day sikhs are originally the first sons of Hindus or their descendents. Even though I am a Hindu, I pray at Gurudwara. I find several sikhs praying at a Hindu temple. In fact, they are treated as Hindus by the temples. Same is true of Jains. They are pure vegetarians and do not eat onions or garlick or even any vegetable grown underneath the earth, like potatoes. These three religions are inter-connected and are very close to each other, alongwith Buddhism. Budhism was started by Gautama Buddha, again another Hindu who preached Ahimsa (Non-Violence). Buddhists a