In religious mythology, heaven is a physical or spiritual realm where people may exist after they die, possibly depending on their actions or beliefs. There are significant differences between religions on what is required to reach heaven. There are major differences between different denominations of Christianity on what is required for salvation.
Heaven and Hell are frequently used to reconcile the inability of humanity to mete out justice during corporeal life. The idea is that even if one can get away with violating human laws, a divine witness/victim/judge/jury/executioner will ensure that no one can avoid perfect justice. According to the argument from justice, if we assume justice must be served and only imperfect justice exists in our earthly lives, therefore an afterlife exists.
The risks and rewards of heaven and hell are the basis for Pascal's Wager.
There is little concrete information on what heaven is supposed to be like. The Bible mostly speaks of praising God for eternity.
Certain sects of Christianity believe that the only requirement to gain salvation and enter heaven is accepting Jesus as your savior, while others believe that keeping the Ten Commandments, doing good works, confessing sins, and/or a number of other requirements must also be met.  The Bible is not entirely clear on the issue, or at least requires significant interpretation.
Some Christians also believe that once they die on earth, their bodies will be transformed and they will enter heaven with "glorified bodies". This idea comes from a number of biblical passages including Philippians 3:20-21
"But our citizenship is in heaven. And we eagerly await a Savior from there, the Lord Jesus Christ, who, by the power that enables him to bring everything under his control, will transform our lowly bodies so that they will be like his glorious body"
Theologian N.T. Wright further explains, "Paul speaks of "the redemption of our bodies" (Rom 8:23 )…he means: God's people are promised a new type of bodily existence…The rest of the early Christian writings, where they address the subject, are completely in tune with this" . Once they receive their glorified bodies and enter heaven, they will live in harmony with the Lord for eternity .
If Heaven exists, Earth is redundant
If heaven, hell and the Christian God exists, he knows how people would act given the chance and if they deserve heaven or hell even before they exist. The purpose of Earth cannot be to test people since God already knows the outcome. God might as well create heaven and hell and send people straight there. This is particularly true if the dogma of predestination is accepted. Therefore, there is little purpose in earthly life and God would not bother creating the Earth. However, since Earth does exist, the conclusion is absurd and the premise "heaven exists" is incorrect. Another possibility is that God created people and is simply seeking a pretext to send people to hell, presumably for his amusement.
- ↑ 
- ↑ The Holy Bible. New International Version.
- ↑ Wright, N.T. "Heaven Is Not Our Home." Christianity Today. 52, no. 4, April 2008, 36-39
- ↑ John 11:25-26 . The Holy Bible. New International Version