You already answered that question in your quote from Revelation 20:4, "And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years. Obviously, some people are in heaven!
That scripture does not say that anyone is presently in heaven.
In fact it plainly describes a future time, after the last trump, at the first resurrection, the beginning of the millennial reign.
John 3:13 prevails.
Nobody is in heaven, nobody is in hell.
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