You are starting with a presupposition that Christianity is uniform in beliefs. It is not.
Ever actually pay attention to Paul’s words?
1 Corinthians 15
21 For since death came through a human, the resurrection of the dead has also come through a human, 22 for as all die in Adam, so all will be made alive in Christ.
Who will be made alive in Christ? Some or all?
Romans 5
18 Therefore just as one man’s trespass led to condemnation for all, so one man’s act of righteousness leads to justification and life for all.
Adam’s trespass led to condemnation for all compared to Jesus whose act leads to justification and life for all. Not some. All.
Colossians 1
19 For in him all the fullness of God was pleased to dwell, 20 and through him God was pleased to reconcile to himself all things, whether on earth or in heaven, by making peace through the blood of his cross.
Through the cross, God reconciled himself to all things. Not some. All.
How does Revelation describe the New Jerusalem?
Revelation 21
25 Its gates will never be shut by day—and there will be no night there.
The gates are never shut. But nothing unclean will enter.
27 But nothing unclean will enter it, nor anyone who practices abomination or falsehood, but only those who are written in the Lamb’s book of life.
Revelation 22
14 Blessed are those who wash their robes, so that they will have the right to the tree of life and may enter the city by the gates. 15 Outside are the dogs and sorcerers and sexually immoral and murderers and idolaters and everyone who loves and practices falsehood.
Those who wash their robes will be allowed to enter by the gates. Those who have not remain outside. But those gates are never closed.