Wasn’t it Christ’s Resurrection that brought in the Kingdom? His Sacrifice was necessary for this, but Christ conquered Death on Easter morning, not Good Friday.
To take it a few steps further, although the gates were open, there was still no “general admission” until Pentecost, where Baptism was given to the Church.
You still seem to link “lack of sin” with heaven. That’s not the case, for we could all earn our way into heaven. Christ is What is necessary to get to heaven. And I am not willing to speak for Him on this matter. I don’t know that Job was not in heaven or John the Baptist, and I don’t think the Church has any official stance on this (I’d be willing to be learn if anyone has this teaching).
You seem to imply that the Kingdom and heaven are one and the same. They are not. Even the Catholic Encyclopedia says, “the ‘kingdom’ means not so much a goal to be attained or a place… it is rather a tone of mind, it stands for an influence which must permeate men’s minds if they would be one with Him and attain His ideals….”
The Prophet Daniel’s vision proves beyond doubt that heaven is not the kingdom spoken of by Christ. Daniel recalls: “I saw in the night visions, and behold, one like the Son of man came with the clouds of heaven, and came to the Ancient of days and they brought him near before him…” Daniel saw [in vision] TWO Personages in heaven – Jesus, the Son and God the Father. Jesus was brought near to the Father and — “And there was given him dominion, and glory, and a KINGDOM, that all people, nations, and languages, should serve him: his dominion is an everlasting dominion, which shall not pass away, and his kingdom, that which shall not be destroyed” (Dan 7:13). Notice that the Kingdom was given in heaven by the Father to the Son clearly showing that the Kingdom is not the heaven of God’s throne.
The Scriptures speak of the Kingdom as something Jesus is preparing for us in heaven and for which He will be bringing back with Him on His return in power and glory. Jesus said, “I will go to prepare a place for you” (John 14:2) and where Jesus went is the heaven of God’s throne. What He prepared there He will bring back to earth as a reward for the faithful: “And, Behold, I come quickly; and MY REWARD IS WITH ME, to give every man according as his work shall be” (Rev. 22:12). At the appointed time – “When the Son of Man shall come in his glory” (Matt. 25:31) – Jesus will say, “Come, ye blessed of my Father, inherit the kingdom PREPARED FOR YOU from the foundation of the world” (Mat. 25:31-34). Jesus here could not have been referring to heaven as the kingdom since heaven is already there and had been in existence even before the first human being was created.
If we confine ourselves to the biblical revelation and not engage in unnecessary speculation, we can never say our reward is a place in heaven, for nowhere in the entire Scriptures is heaven promised as the reward of the saved. When Jesus Christ appeared on earth, He never once said anything about human beings going to heaven. Have you ever wondered why Jesus never said something like, “If you want to go to heaven, do this and that”? Even the Jews at the time knew the God of their fathers never promised heaven as a reward for the righteous. That’s why we do not find anyone asking Jesus: “How can I go to heaven?” Rather, the question had always been, “How can I have eternal life?”
The Scriptures are full of information about how we may have eternal life, but none about how we may get to heaven. The Jews knew about this and Jesus acknowledged that truth. He said: “Search the scriptures; for in them you think you have eternal life…” (John 5:39).