Christianity is the only religion that teaches man can do nothing to earn or pay his way into heaven. Man, a slave to the sin nature he was born with, must completely rely on the grace of God in applying Jesus Christ's sacrifice to the sins of the believer. Upon death, the spirits of Christians go to a temporary paradise, while the spirits of unbelievers go to another temporary holding place. At the final judgment, Christians are given a new body and spend eternity with God in paradise, while unbelievers are separated from God for eternity in hell.
IT IS WRITTEN: Ecclesiastes 9:5 For the living know that they shall die: but the dead know not any thing, neither have they any more a reward; for the memory of them is forgotten. Isaiah 26:14 They are dead, they shall not live, they are deceased, they shall not rise: therefore hast thou visited and destroyed them, and made all their memory to perish. Hebrews 9:27 And it is appointed unto man once to die, but after this the judgment.
My personal belief? Which is admittedly only an opinion as the Bible does not indicate specifically. I believe it likely there is a place, call it purgatory or the Bosum of Abraham or whatever, where 'souls' for lack of a better word or concept, go to rest or wait until Christ comes again to winnow His from Not His. NOT a place you can get prayed out if or where anything happens, just a sort of waitiing place until the dead in Christ are called to rise and Not His will be sent on their way.
If you confess that Jesus died on the cross for your sins and believe that He rose again to overcome death you will spend eternity with the Lord, if you don't, you will suffer eternal separation from God and His love. This is called Hell.
As the Catechism says, death puts an end to human life as the time open to either accepting or rejecting the divine grace manifested in Christ. In other words there are no opportunities to grow in holiness, no second chances. After we die we immediately stand before the judgement seat of Jesus and He will reward us based on how we have lived our lives, on how we have responded to the blessings and graces He gave us. This is called the particular judgement, because it refers to each of us individually. If we have died in the state of grace, we will go to Heaven or spend some time in purgatory. If we have died in a state of mortal sin, we will immediately go to Hell. Many of our culture are afraid of death. Why? Probably because they do not really grasp the meaning of life. We need to prepare ourselves for death by living our lives as Jesus calls us to, by loving Him with all our strength and loving our neighbors as ourselves. Many of the great saints longed for their time on earth to come to an end so that they could go home to be with the Lord. They were unafraid of death because they understood the purpose of life and lived it: They loved.