The question of how God judges those who do not know Christ has been on my mind for quiet a while as it has been repeatedly requested of me to provide just reason for the basis of His judgment.
I realize that not knowing Christ is not the same as rejecting Him, because if a person does not know there is a real Jesus to know, they cannot be justly judged for not knowing Him. However, the judgment that comes from God is based on our own moral standard that we hold others to, which we ourselves have failed to uphold. While His standard is higher than our own, He judges the one who does not know Him based on the laws that person holds to be the moral standard.
So let’s say a person’s value system says that intolerance is wrong and makes judgments against people who are intolerant. Then that same person is intolerant in some way, they will be held accountable to God for breaking their own moral standard.
Romans 2: 1-6 You, therefore, have no excuse, you who pass judgment on someone else, for at whatever point you judge the other, you are condemning yourself, because you who pass judgment do the same things. Now we know that God's judgment against those who do such things is based on truth. So when you, a mere man, pass judgment on them and yet do the same things, do you think you will escape God's judgment? Or do you show contempt for the riches of his kindness, tolerance and patience, not realizing that God's kindness leads you toward repentance?But because of your stubbornness and your unrepentant heart, you are storing up wrath against yourself for the day of God's wrath, when his righteous judgment will be revealed. God "will give to each person according to what he has done."
Thus God’s judgment is not based on holding someone accountable to some standard they didn’t know existed, but by holding them accountable to their own standard that they practice as true. This is affirmed in Revelation when it is talking about that ultimate Day of Judgment.
Revelation “And I saw the dead, great and small, standing before the throne, and books were opened. Another book was opened, which is the book of life. The dead were judged according to what they had done as recorded in the books.”
The judgment then justly comes based on what is justly deserved according to what is known. The wording of “the dead” refers to those who are not in the life of Christ. The good news though, is that none of us have to pay that debt to sin. None of us have to come under judgment. We can instead be justified—having Christ death be substituted for our death—joining with Him in His Resurrection, being fully made whole without any debt to sin. We do not have to earn that redemption; we simply take hold of His hand that is extended out towards us. It’s like reaching up with an empty hand, knowing you have nothing to offer, but receiving Him forevermore.