A classic illustration from Francis Schaeffer:
If every little baby that was ever born anywhere in the world had a tape recorder hung about its neck, and if this tape recorder only recorded the moral judgments with which this child as he grew bound other men, the moral precepts might be much lower than the biblical law, but they would still be moral judgments.
Eventually each person comes to that great moment when he stands before God as judge. Suppose, then, that God simply touched the tape recorder button and each man heard played out in his own words all those statements by which he had bound other men in moral judgment. He could hear it going on for years—thousands and thousands of moral judgments made against other men, not aesthetic judgments, but moral judgments.
Then God would simply say to the man, though he had never head the Bible, now where do you stand in the light of your own moral judgments? The Bible points out . . . that every voice would be stilled. All men would have to acknowledge that they have deliberately done those things which they knew to be wrong. Nobody could deny it.
We sin two kinds of sin.
We sin one kind as though we trip off the curb, and it overtakes us by surprise.
We sin a second kind of sin when we deliberately set ourselves up to fall.
And no one can say he does not sin in the latter sense. Paul’s comment is not just theoretical and abstract, but addressed to the individual—“O man”—any man without the Bible, as well as the man with the Bible.
. . . God is completely just. A man is judged and found wanting on the same basis on which he has tried to bind others.
—Francis Schaeffer, The Church at the End of the Twentieth Century, 2d ed. (Wheaton: Crossway, 1985), 49-50.
Consider the principles set forth in Romans 2:
1 Therefore you have no excuse, O man, every one of you who judges. For in passing judgment on another you condemn yourself, because you, the judge, practice the very same things. 2 We know that the judgment of God rightly falls on those who practice such things. 3 Do you suppose, O man—you who judge those who practice such things and yet do them yourself—that you will escape the judgment of God? . . .
14 . . . When Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. 15 They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them 16 on that day when, according to my gospel, God judges the secrets of men by Christ Jesus.
For more thoughts on this, see Sam Storms’s helpful blog post.
The best book I know of on this and related question is Robert Peterson and Christopher Morgan’s excellent edited volume, Faith Comes by Hearing: A Response to Inclusivism (IVP, 2008).