Scripture gives no formula, but something better: a Judge who reads every heart, holds people accountable for the light they actually had, and desires everyone saved. No one is condemned for the religion they were born into, and wherever anyone is saved, it is always through Christ.
The Grace Answer
This question troubles thoughtful people for good reason. It feels unjust that someone's eternity might hinge on where they happened to be born. Scripture does not hand us a formula that resolves every case, and anyone claiming total certainty here has gone past the text. But it gives us solid ground to stand on.
Start with what we can say plainly. God does not judge religious labels. A person is not condemned merely because the word Muslim or Hindu describes the family and culture he was born into, any more than a person is saved merely because the word Christian sits on a membership roll or a survey. God judges hearts, not categories. He knows the light each person received, the opportunities they had, and how they responded. The label attached to someone by birth simply does not give us enough to pronounce their eternity.
Judgment fits the light
Scripture is clear that God judges people according to what they could actually know. Paul says those who sinned without the written law are not judged as if they had it, and that Gentiles without the law can still show its work “written in their hearts, their conscience also bearing witness.” Jesus taught the same principle: the servant who knew his master's will is held more accountable than the one who did not, because “to whom much is given, from him much will be required.” God does not hold anyone responsible for truth that was never available to them. His judgment is informed, proportionate, and perfectly just.
This does not turn conscience or sincerity into a second way to God. Conscience can accuse or excuse, but it cannot make anyone righteous, and a person can be entirely sincere and still be wrong. So we do not say, he is devout, therefore he is saved. We say something more honest: God alone knows whether a person was responding to the light he had, resisting it, or reaching toward a God he did not yet clearly understand. Wherever salvation happens, it happens through Christ and His finished work, never through human sincerity.
How Christ's work reaches partial light
But how could that reach someone who never heard the name? The Old Testament saints are the pattern. Abraham was counted righteous by faith long before the cross, saved by trusting the God who had actually revealed Himself to him, even without the full picture of the gospel. Salvation always ran through Christ, even for those who could not yet name Him. And Cornelius shows the balance: God noticed this devout, praying Gentile and did not ignore him, yet He still sent Peter with the gospel so he could hear and believe. The pattern is not that seekers are left in the dark. It is that God sees a heart reaching toward Him and knows how to bring it more light.
So we hold this with both hope and humility. We do not say everyone who never heard is automatically lost, because Scripture ties judgment to the light a person had. We do not say every sincere religious person is saved, because that would make sincerity a substitute for Christ. What we say is this: Christ alone saves, God weighs every heart with perfect knowledge, and “the Judge of all the earth” will do right. That is not a dodge. It is trusting the character of a God who desires all to be saved and proved it at the cross, leaving the details we cannot see safely in His hands.