the popular beleif in sikhism is the following
Sikhism FAQs:What happens to the individual after death?
Q29. What happens to the individual after death?
Human life is just a stage in the upward march of the soul. The individual has got birth as a human being, after going through lower forms of life. Human life is the final stage in the soul's progress to divinity. It is for us to make the most of this opportunity and thereby end our cycle of transmigration.
Death means the destruction of the physical self. The ashes and bone dust mix with the elements. But the soul which leaves the body, awaits a new dwelling. Just as a person casts off worn-out garments and puts on other that are new, so the subtle soul casts off the worn-out body and dwells in a new form. If there were no continuance of the soul after death, how could it become perfect to merit union with the Almighty?
Sikhism believes in the immortality of the soul. The devotee has no fear of the pangs of death. In fact he welcomes death, because it gives him a chance for the merger into Divinity. The evil person, however, dreads death. For him, it will lead to the unending cycle of birth and death. After death, man comes to the next birth according to what he deserves. If he has been wicked and evil, he takes birth in the lower species. If he has done good deeds, he takes birth in a good family. The cycle of birth and death keeps the soul away from Divinity. It can merge with God, only if the individual, by spiritual effort, has amassed the capital of the Name(the Holy spirit as understood by Christians) and thus lives with the Holy Spirit.
Guru Arjan in the Sukhmani dwells on the sad plight of the soul which is not endowed with the Name. The soul in its lonely march through darkness can only find sustenance in the word of God. Otherwise it feels the weariness and pain of isolation.
The soul, Jiva, is a part of God. It is deathless like Him. Before creation, it lived with God. After Creation it takes bodily forms according to His Will. The soul is, however, nourished by virtue and meditation on "The name". The transmigration of the soul can come to an end by meditation and divine grace.
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for more of your question on sikhism you can read the following faqs
Sikhism FAQs:Index
Does anyone know what sikhism teaches about afterlife... or if there even is an afterlife. I always here so many different things and am confused on whether there is heaven/hell and or if we believe in reincarnation. And if there is a heaven... how does one get there? Does being a good sikh guarantee that? What exactly is a GOOD sikh? I'm sorry about the leading questions but one question always leads to another... 
