If you want to give yourself a real headache, try coming to grips with the thought of eternity... forever. As humans, we are confined by time, so eternity is hard to comprehend. But I once heard an example of eternity that helped me have an “Aha!” moment, and I want to share it with you.
Imagine that the only living organism left on our planet is a bird that can never die. Meanwhile, the world's mountain ranges—the Smoky Mountains, the Rockies, the Himalayas, the Alps, and all the rest—are but heaps of sand. Now suppose the bird can take one grain of sand every thousand years and drop it into the ocean. Inevitably, as time runs its course, the bird will grab that last grain of sand ... and eternity will have just begun. Now that's a long time.
Or is it?
Actually, time does not exist in eternity. Eternity is a timeless reality that knows no end. We were all created to exist forever. The question is, where? Does the Bible teach that hell is eternal? Indeed, it does. Is heaven eternal? Indeed, it is.
In Matthew Chapter 25 Verse 46, Jesus says some shocking words. He warns about the final judgment and shares how the nations will appear before Him. Jesus describes how the sheep (saved; people who trust and believe in Jesus Christ) and the goats (unsaved; people who don't trust and believe in Jesus Christ) will be separated. He says, "These will go away into eternal punishment, but the righteous into eternal life".
Believers will experience eternal life, and nonbelievers, eternal punishment. Remember, God is giving YOU a choice right now. You can no longer stand before a Sovereign God and say, "I didn't know."
So who goes to heaven?
HEAVEN IS A PROMISE TO FOLLOWERS OF JESUS CHRIST (the only God/Man)
God, the Creator of the universe, has PROMISED heaven to you... if you believe in His Son's death, burial, resurrection and ascension, with your repentance. (Repentance in Christianity means a sincere turning away, in both the mind and heart, from self to God. It involves a change of mind that leads to action--the turning away from a sinful life to obeying God.)
Jesus promised all believers a place in Heaven. (John 14:1-4)
“Do not let your hearts be troubled. You believe in God; believe also in me. My Father’s house has many rooms; if that were not so, would I have told you that I am going there to prepare a place for you? And if I go and prepare a place for you, I will come back and take you to be with me that you also may be where I am. You know the way to the place where I am going.”
God's promise is simple.
Believe in God + Believe in Jesus and what He did for YOU + Repentance of your sins = Heaven is yours eternally. A place joy, rest and peace that has been prepared for YOU forever.
You can learn more about Heaven than many, many believers who haven't even bothered to investigate. It's like people moving to Tahiti (an earthly kind of paradise) and know nothing about this place before arriving there.