Who said heaven is located on the other side of death? Jesus did not! What did he say about heaven? You will find in the Sermon on the Mount: Heaven belongs to “the poor in spirit” and to those “persecuted for righteousness sake” and it will be available only to those who are more righteous than the religionists, scribes and Pharisees. (Matt. 5)
Asking for entrance into heaven will not do it - only doing the will of the Father. (Matt. 7)
And then in Matthew 23, this fierce rebuke: “But woe unto you, scribes and Pharisees, hypocrites! for ye shut up the kingdom of heaven against men: for ye neither go in yourselves, neither suffer ye them that are entering to go in.”
Whoa! “Shutting up the kingdom of heaven against men!” By teaching that heaven is not reachable except through death (if you are lucky), so don’t bother trying to relinquish your false idols and to raise yourself up in this present life.
I find no indication in the Gospels that death is a prerequisite for entrance into heaven. - far from it! Notice that Jesus’ Ascension proceeded from his Resurrection, not his crucifixion.
“Heaven is not a locality, but a divine state of Mind in which all the manifestations of Mind are harmonious and immortal, because sin is not there and man is found having no righteousness of his own, but in possession of ‘the mind of the Lord,’ as the Scripture says.” (Science and Health with Key to the Scriptures by Mary Baker Eddy)
“Having no righteousness of his own” was the example Jesus laid before us - to follow - not something the typical religionist is interested in.
The following audio interpretation of Revelation xxi: 1 culminates with: "remember Jesus' words, 'The kingdom of God is within you.' This spiritual consciousness is therefore a present possibility."