In the article "Martyrs' HOPE," we provided many quotes from the earliest Christian apologists - martyrs describing the Christian hope handed down to the early Christians by the Apostles. It was not an eternal destiny in heaven, but the resurrection of the physical body and an eternal inheritance in the Land God promised to Abraham and to his 'Seed' (who is Christ), when the curse is to be removed from the earth. This hope gave the early martyrs courage to overcome the most severe torture and persecution.
If this is what the Apostles taught, where did the idea of 'heaven' as the eternal inheritance come from? The answer is not hard to find for those familiar with paganism and Greek philosophy. The pagans developed a mythology of afterlife in the "underworld." No doubt, this was because corpses were buried in the earth. In ancient paganism, the afterlife was seen as a further descent into the underworld. However, around the 5th century BC, Greek influence greatly altered this pagan view, from a descent into Hades to an ascent of the soul into heaven.
"When the concept of the soul was further developed in the Greek world, a sharp distinction was made between the mortal body and the immortal soul which originates in the divine world. Only the latter journeys in the world to come. The idea of a journey of the soul now makes its appearance in Greek literature. According to the Orphic writings (6th - 5th century [BC]), which introduce the idea, the goal of souls is to return to their heavenly home after long travels. Hades now becomes the place of punishment, hell. Plato introduced into Greek philosophy the belief of the immortality of the soul and its many [re]incarnations up to the goal of final purification. According to the myth ... the soul goes to the place of judgment after leaving the body. There the judges order the righteous ... to ascend to heaven. ... The idea gradually changes from a descent of the soul to the underworld, to an ascent of the soul into heaven. The descent becomes an ascent." 
Plato taught that souls lived in heaven before being born into this creation, and that they ascend back to heaven when they have sufficiently learned philosophy after a series of reincarnations. He taught that the material body causes the corruption of the soul. Thus, the destiny of the body was to decay into dust. But the hope of the soul was to be released from the material flesh, to leave this physical creation and to ascend into heaven as pure spirit. Both the physical body and the physical creation were seen as prisons of the soul, for which the soul longed for release. Consequently, the Christian hope of the resurrection of the flesh and an eternal Land inheritance within this creation were foreign ideas to the Greek mind.
The Apostle Paul and his Gospel were mocked at the philosophical forum at Athens when he mentioned the resurrection of the dead. The ancient Christian "hope" left the Greek intellectual scoffing. Paul warned the early Christians to avoid Greek philosophy, which he called "foolishness," the "wisdom of men" in contrast to the "wisdom of God," "profane and idle babblings," something to be avoided as "knowledge falsely so called," which had caused those professing it to have "strayed concerning the Faith." 
But, late in the second century, as the early apologists of Christianity who defended the Apostolic Faith fell in martyrdom, a new breed took their place. These men were not personally acquainted with the Apostles, nor were they pastors of local churches. They were 'baptized' students of Greek philosophy. Thus the age of the Christian 'apologist' began to decline, and the age of the 'theologian' was born. These early theologians had little interest in defending the pristine Faith as handed down by the Apostles. They were on a mission to make Christianity a respectable philosophy to the Greek mind, and able to compete in the philosophical arena of intelligentsia.
Physical matter itself was the source of the soul's corruption in the Greek mind. The only way for the new Christian 'theologians' to make Christianity palatable was to incorporate the pagan philosophy and hope into Christianity. They also borrowed the "allegorical" method of interpretation from the mystery religions and Gnosticism in order to explain away the promises contained in the Old Testament Scriptures about the restoration of Jerusalem, the Land, and the resurrection of the flesh. They simply claimed that all the prophecies about resurrection and restoration of Jerusalem, God's people, and the whole earth, were mere allegories of Plato's heavenly spheres.
In Plato's system, the earth was a stationary sphere at the center of the universe. The sun, moon, and planets were each attached to a solid but transparent crystalline sphere, one inside the other. Each sphere rotated independently, which is the cause of the movement of the heavenly bodies. The first transparent sphere (outward from earth) carried the moon; the second carried the sun; the third carried Venus; the fourth carried Mercury; the fifth carried Mars; the sixth carried Jupiter; the seventh carried Saturn; the eighth carried the fixed stars. God existed beyond the sphere of the fixed stars. In Plato's scheme, the soul's ascent was progressive, away from earth, ascending one sphere at a time. In each sphere the soul must learn philosophy sufficiently until he is able to ascend into the next sphere. Eventually, the soul could potentially reach God.
Clement of Alexandria and his pupil and successor, Origen, were such theologians, intent on repackaging Christianity in a Platonic mold. Clement and Origen turned Jesus into an apologist for Plato, rather than seeing Him as affirming the Hebrew Prophets. Jesus' "many mansions" statement in John 14 was the "proof text" they used to show that Jesus was a Platonist, affirming Plato's 'heavenly spheres.' It mattered not that the disciples to whom Jesus spoke would certainly have understood Him as affirming the Hebrew prophecies, not Plato's pagan cosmology.
In his opening words in Stromata, Clement of Alexandria had nothing but praise for Plato and his companions, placing the writings of the Greek philosophers on a par with inspired Scripture.
"Accordingly, before the advent of the Lord, philosophy was necessary to the Greeks for righteousness. And now it becomes conducive to piety; being a kind of preparatory training to those who attain to faith through demonstration. 'For thy foot,' it is said, 'will not stumble, if thou refer what is good, whether belonging to the Greeks or to us, to Providence.' For God is the cause of all good things; but of some primarily, as of the Old and the New Testament; and of others by consequence, as philosophy. Perchance, too, philosophy was given to the Greeks directly and primarily, till the Lord should call the Greeks. For this was a schoolmaster to bring 'the Hellenic mind,' as the law, the Hebrews, 'to Christ.' Philosophy, therefore, was a preparation, paving the way for him who is perfected in Christ." 
According to Clement, Plato was the forerunner of Jesus Christ for the Greek mind. Thus, he interpreted Jesus' words in a Platonic paradigm, where the soul progressively ascends after death through a series of heavenly spheres, by means of philosophical education, into eventual union with God in heaven. Jesus was merely the first to ascend to this higher existence.
"For there are with the Lord both rewards and ‘many mansions’ corresponding to men’s lives. ‘Whosoever shall receive,’ says He, ‘a prophet in the name of a prophet, shall receive a prophet’s reward; and whosoever shall receive a righteous man in the name of a righteous man, shall receive a righteous man’s reward; and whoso shall receive one of the least of these my disciples, shall not lose his reward.’ … They shall work, therefore, in accordance with the appropriate mansions of which they have been deemed worthy as rewards, being fellow-workers in the ineffable administration and service. ‘Those, then,’ says Plato, ‘who seem called to a holy life, are those who, freed and released from those earthly localities as from prisons, have reached the pure dwelling-place on high.’ In clearer terms again he [Plato] expresses the same thing: ‘Those who by philosophy have been sufficiently purged from those things, live without bodies entirely for all time. Although they are enveloped in certain shapes; in the case of some, of air, and others, of fire.’ He adds further: ‘And they reach abodes fairer than those, which it is not easy, nor is there sufficient time now to describe.’ Whence with reason, [Jesus said] 'blessed are they that mourn: for they shall be comforted'." 
Origen, Clement's pupil and successor, developed the association of Plato's heavenly spheres even further.
"We shall be caught up in the clouds to meet Christ in the air, and so shall we ever be with the Lord.’ We are therefore to suppose that the saints will remain there until they recognize the twofold mode of government in those things which are performed in the air. ... I think, therefore, that all the saints who depart from this life will remain in some place situated on the earth, which holy Scripture calls paradise, as in some place of instruction, and, so to speak, class-room or school of souls, in which they are to be instructed regarding all the things which they had seen on earth. … If anyone indeed be pure in heart, and holy in mind, and more practiced in perception, he will, by making more rapid progress, quickly ascend to a place in the air, and reach the kingdom of heaven, through those mansions, so to speak, in the various places which the Greeks have termed spheres, i.e., globes, but which holy Scripture has called heavens; in each of which he will first see clearly what is done there, and in the second place, will discover the reason why things are so done: and thus he will, in order, pass through all gradations, following Him who hath passed into the heavens, Jesus the Son of God, who said, “I will that where I am, these may be also.” And of this diversity of places He speaks, when He says, “In My Father’s house are many mansions.” 
During the third century when these 'theologians' held great influence, there were still many pastors and martyrs who held firmly to the pristine Faith taught by the Apostles. Yet, the influence of the new seminary of Clement and Origen greatly impacted Christian thinking, throwing Christianity into confusion between a "Jewish" based Christianity and a sophisticated "Greek" version. As the Jews themselves were increasingly looked on with disdain, so too was the Jewish hope that had been the foundation of Apostolic Christianity.
With the conversion of the Emperor Constantine, and his declaring 'Christianity' the official religion of Rome, the squabble among Christians over the eternal destiny of the redeemed had to be settled once and for all. Constantine himself cast a large shadow over the Nicene Council which he convened for the Christian bishops. And in his opening address, he made it perfectly clear which of these "hopes" ought to be adopted as the official view of the new Roman Church-State. He sided decisively with Plato and his Alexandrian devotees, Clement and Origen, and against the earlier apologists and martyrs.
"Plato … plainly declares that a rational soul is the breath of God, and divides all things into two classes, intellectual and sensible: consisting of bodily structure; the one comprehended by the intellect alone, the other estimated by the judgment and the senses. The former class, therefore, which partakes of the divine spirit, and is uncompounded and immaterial, is eternal, and inherits everlasting life; but the latter, being entirely resolved into the elements of which it is composed, has no share in everlasting life. He [Plato] farther teaches the admirable doctrine, that those who have passed a life of virtue, that is, the spirits of good and holy men, are enshrined, after their separation from the body, in the fairest mansions of heaven. A doctrine not merely to be admired, but profitable too. For who can believe in such a statement, and aspire to such a happy lot, without desiring to practice righteousness and temperance, and to turn aside from vice?" 
"If indeed we in any sense aspire to blessedness like that of God, our duty is to lead a life according to his commandments: so shall we, having finished a course consistent with the laws which he has prescribed, dwell forever superior to the power of fate, in eternal and undecaying mansions. … raising our affections above the things of earth, and directing our thoughts, as far as we may, to high and heavenly objects: for from such endeavors, it is said, a victory accrues to us more valuable than many blessings." 
Not a few bishops were dazzled by Constantine, including Eusebius, the church historian. Pleasing the new 'Christian' emperor became a very high priority among many bishops. His royal favor was a great incentive to set apart their doctrinal differences, even overpowering for some the incentive to please Christ. And Constantine lavished church leaders with honor and wealth when they pleased him and assisted him in achieving his goals. Those who did not go along with the program were labeled 'heretics' and 'schismatics'; their properties were seized and they were forbidden to congregate for worship.
This was the birth of the Roman Catholic Church, with the backing of political Rome. It was a blend of paganism and Christianity. The Protestant Reformers simply adopted the same philosophical 'Christianity' as Rome, with some notable changes. Yet, the eschatology of Rome and the Platonic presuppositions remained, giving us the Protestant eschatology called amillennialism.
Dispensationalism came later as a hybrid of amillennialism and the ancient hope. It simply adopted the Pharisees' view that the land inheritance was promised exclusively to the physical descendants of Abraham (without regard for their acceptance of Christ). Yet for the "Church," dispensationalists maintained the same Platonic heavenly destiny as amillennialism, which originated in Greek paganism.
 Kittel, Gerhard, Theological Dictionary of the New Testament, Vol. VI, p. 568  1 Cor. 1:18-25; 1 Cor. 3:18-20; 1 Tim. 6:20-21  Clement of Alexandria, Stromata, Bk. I, ch. v  Clement of Alexandria, Stromata, Bk. IV, ch. vi  Origen, De Principis, Bk. II, ch. xi  Eusebius, Oration of Constantine, ch. ix  Eusebius, Oration of Constantine, ch. xiv