How can God justify sending someone to the lake of fire who never heard the gospel?
God can justify that judgment because He is never unjust and never unfair. Although the human response protests that it is not fair and that such people never had a chance, the only answer to the dilemma is God's unwavering justice. Paul declares God's righteousness, and He remains just in His dealings.
Les explains that this is a question he has had in his mind and assumes everyone has: How will God justify sending someone to the eternal lake of fire when, so far as we know, they never had an opportunity to hear the gospel? The human response is to say, But God, that's not fair; they never had a chance. Les says the only way to answer that dilemma is that God is never unjust and never unfair. In the surrounding passage, Paul is declaring God's righteousness and reminding us that we have nothing good, no righteousness, and nothing to barter. We are helpless and hopeless, like Israel at the Red Sea, but that is when God steps in, so that He might be just. The answer ultimately rests on God's perfect justice and fairness, not on human protest.