Some additions and comments on reul's post (from a Sikh in training's point of view and that of Sikhs):
It should also be pointed out that in Guru Nanak's time, the Sikhism was a pacificist religion. It wasn't until much later that they acquired their now famous reputation as swordsmen.
Yes..and no. In historical analysis of action, this is true because the Sikhs did not begin to engage in combat immediately from the inception of the religion, but only after the Mughal Empire Jahangir declared that it would seek to destroy the religion. After that proclamation, the fifth Sikh Guru, Guru Arjan Dev was tortured for five days, after which he left his human body. The Sikhs then began an armed resistance and all out battle against the oppressive regime. However, Guru Nanak himself went on journeys and challenged much of the status quo, even to challenging the Mughal Emperor of the time face to face for his brutal conquest of India. Though not an armed battle, the essence of resistance to tyranny was present from the very beginning.
It's the most successful of the so-called Sant movements, a general popular blending of Hindu and Muslim mysticism in Northern India in the early 2nd millenium. All of these Sant derivatives share a belief in a formless, absolute God with whom one can experience contact through meditation and other austerities. Nanak, Sikhism's founder, compiled several scriptures from various religions into texts (the Adi Granth and Guru Granth Sahib) which are deemed helpful in this regard. Because Sikhism is experiential rather than scholastic or prayer-based, there's a heavy emphasis on teacher (guru) reverence, as the techniques to achieve such mystical experience must be guided by one who has already accomplished it.
Blending of Islam and Hinduism is a common reference given by scholars about Sikhism
a categorization that makes many Sikhs unhappy. Sikhism, according to its very scriptures that were directly written by the Gurus themselves, states that the knowledge of the religion was directly passed down from the Almighty to the Gurus. The Gurus do not ever show an analytical attempt of melting the two religions religions together. Rather, the scriptures point out the many hypocrisies of both faiths (caste system, treatment of women as inferior etc). The same is applied to calling Sikhism a Sant movement. At the time of Guru Nanak, a movement called the Bhagti movement was occurring that was challenging many of the Hindu status quo in India. However, this movement mostly took place within the boundaries of the Hindu religion. Guru Nanak, however, himself broke away from all the prevalent conventions of the current religions present and started his path. The analysis that Sikhism is a blending of two religions does not remain valid when Sikhism is compared to other religions and commonalities are found there also.
Sikhism also does not put any faith in austerities, or extreme penances (read as physical tortures to please the Almighty) and has many verses that speak against such practices. The Sikh philosophical basis revolves around three principles laid down by Guru Nanak himself: Naam Japna (to meditate and remember the Almighty), Vand Kae Chakna (to share with others and then partake yourself of your possessions), and Kirat Kamani (to earn wages by honest means).
As per scriptures, the Adi Granth and the Guru Granth Sahib are both essentially the same scripture. The Adi Granth was the name of the sacred scripture up to the time the last Guru, Guru Gobind Singh was alive. Before passing, he passed down the Guruship to the Adi Granth Sahib, which took on the title of Guru Granth Sahib henceforth and serves as a guiding light of the Sikh religion till now and to the future. Therefore, the reverence is given to the message contained in the Guru Granth Sahib, and never is that same reverence ever granted to any human.
Sikhism thrived under the tolerant Muslim rule of the early Mughals, but later on, in reaction to increasing religious conservatism under the Emperor Aurangzeb, they reorganized as a martial community in which all men were expected to be armed and trained to fight to defend justice (theirs or someone else's). The last Guru, Gobindsingh, disbanded the guruship and created the Khalsa (pure), a warrior caste sworn to fight for Sikhism's principles.
True about the Mughal rule. As noted above, Jahangir decided that the increasingly powerful Sikh religion (Sikhism by the time of the fifth Guru had gained many followers) must be destroyed and therefore, had the fifth Guru arrested and tortured to death. Guru Hargobind Sahib, upon being appointed Guru instructed the most respected Sikh, Baba Buddha, to make his appointment official by placing a sword on his person. Baba Buddha placed one sword on Guru Hargobind Sahib, after which Guru Hargobind Sahib requested another sword be placed on his other side. The two swords came to be known as Miri-Piri, or the Temporal/Worldly/Martial and the Spiritual. The Miri was 38 inches long and the Piri was 40 inches long. This is symbolic because the Sikh also embodies this concept of Miri-Piri, meaning that both concepts are present, BUT the spiritual is always to be the dominant power in that Sikh and is to be the guiding force behind the Martial power.
The Khalsa was not a martial caste. Casteism is anti-thetical to Sikh beliefs. Actually, the Khalsa Sikhs are the Sikhs. Guru Gobind Singh Ji, in April 1699, summoned his followers to his fort at Anandpur Sahib and created the Khalsa Panth, or the Community of the Pure. He encouraged all his followers to become members of the Khalsa Panth and become brothers and sisters. That was the end of the mission of the human Gurus
to create the Khalsa, which was the final and true form of the Sikh. Others who are not yet ready to take on that ommittment, but are slowly training themselves to become a member of the Khalsa Panth are known as Sehajdharis, or slow adopters. They are not yet officially Sikhs, but are striving towards that goal.
In 1799 the Sikh Raja of Lahore, Ranjit Singh, united all the Sikhs of Punjab into a Sikh Empire which was staffed with European officers and weapons. After he died, though, infighting led to direct intervention by the British, and later troubles led to a second war in which the British annexed the entire Punjab. Sikhs, though, ended up being loyal imperial troops, and their exploits in campaigns through WW2 have made them famous worldwide.
Maharaja Ranjit Singh, for the first time, did something that nobody else had done. He was able to secure and control the Khyber Pass and build forts along it. This was the gateway for every invasion into India by every foreign power and solidified the boundary between Afghanistan and olden India (India and Pakistan). After Maharaja Ranjit Singh died, there was indeed in-fighting between inept successors, but the reason the Sikh Raj fell was because the most trusted generals betrayed the Sikhs. There names are Lal, Gulaba and Dhian Dogra. They negotiated with the British and sabotaged every single Sikh battle against the British, which finally led to their defeat. However, the British recognized that without the treachery, they would have been run out of India by the Sikhs and decided to enroll the Sikhs in heavy numbers in their armed forces. The British also recognized that the Sikh religious discipline was the key to their battlefield prowress and stated that any Sikh violating any tenets of their religion while in the service would be court-martialed and discharged. Of course, at the same time, the British also tried (and failed) to alter Sikh history to their favor.
In recent times there has been a push by radical Sikhs to break away from India to form "Khalistan," an independent Khalsa/Sikh state. The selection of a Sikh to be the current Indian prime minister is thought to have been an appeasement to Punjabi separatists.
The Khalistan movement was the response to the Indian government (especially Indira Gandhis) slanted policies against the Sikhs, the culmination of which was a military operation against the Sikh place of worship, the Harimandir Sahib (aka. The Golden Temple). This involved the deployment of commandoes, thousands of armed soldiers and a tank division onto the Harimandir Sahib complex. After the three-day siege against 40 or so Sikhs, the campaign resulted in thousands of Sikhs killed. Subsequently, Indira (who had authorized the campaign) was assisinated by her Sikh bodyguards. This led to a massacring of Sikhs across India, leaving 10,000 Sikhs dead, raped, looted and otherwise devastated. This provoked a strong response from the Sikhs, who had directly lost family members or knew of someone affected by the events. Many Sikhs launched a campaign to punish those who had been responsible for the killings (most of whom were government officials
in the November genocide after Indiras assissination, the mobs that killed Sikhs were led by government officials to selectively attack, pillage and loot Sikh houses and businesses) that the judicial system turned their back to. Talk of independence was also expressed in the movement, but the movement was mostly involved in getting justice for those who were so brutally killed in the government-sanctioned killings.
The appointment of the current Priime Minister of out os his merits. While being finance minister, Manmohan Singh implemented policies that are still yielding fruition in India. His record is unblemished and his ideology to governing is simple. He was chosen because he was the best man for the job, not on the basis of his religion.
Any further inquiries, feel free to post. Glad to answer any questions.