It is only due to a shared geographic culture that some ideas or methods of these different religions may seem similar. Sikhism is in fact a unique revealed religion. It is not derived from any other religion. It is not a blend of any two or three religions. Guru Nanak started a new faith.
The uniqueness of the Sikh faith is immediately apparent if you understand the main philosophies and practices of the Sikhs. In fact Sikhism questions, challenges and rejects many of the practices of Hinduism and Islam. For example, according to Sikh teachings, all people are created equal regardless of gender, status, geographic location, and religion affiliation. Sikhs strive to achieve a balance between spiritual life and temporal life.
Sikhism condemns empty rituals. Sikhs do not believe in pilgrimages, idolatry or reverence to pictures. Sikhs believe in practices such as daily prayer that instill understanding and discipline.
The Sikh scripture, the Guru Granth Sahib, is the only major religious text which contains writings by teachers of other faiths. This is because the Sikh Gurus taught that there are many different ways of achieving a connection with the God. The Sikh way is one of these ways. If you are following the Sikh way, you must follow it to the best of your abilities, and with absolute devotion.
No. Sikhism forbids proseylization or forced conversions. Sikhism believes that there are many paths to God. That said, Sikhism welcomes anyone interested in learning about the religion. Thus, people might learn about Sikh faith and then even be baptized as Sikhs. There are Chinese Sikhs, African Sikhs etc. However, once someone is baptized and initiated as a Sikh, she or he must follow the Sikh path to the best of her or his ability.
Sikhs’ focus is on this lifetime. The Sikh Scripture ask Sikhs to make the best of their time on this earth, for this is one’s opportunity to accomplish her or his best and to make a connection with Waheguru—the One, Omnipotent Power. Sikhs are asked not to partake in rituals and superstitions and not to concentrate on what occurred before birth or after death. Sikh scripture repudiates a belief in a physical place called Heaven or Hell. Similarly, Sikhism rejects the notion of a Judgment Day.