In saying this, in espousing what is sometimes called “exclusivism,” I should be clear what I am not saying.
1. I am not saying there is nothing decent or honorable in other religions or in people from other religions. Ultimately, there is no good deed apart from faith, but Christians should recognize that Muslims, Buddhists, Hindus (and secular atheists for that matter) can be charitable, honest, and kind. Exclusivism does not demand that we reject everything about every other belief or every other religious person. What we do believe is that the most important doctrines of the Christian faith are not shared by other faiths and that even the most moral neighbor cannot be saved by good works.
2. I am not saying that Christianity is nothing more than saying the right prayer. Often in deriding exclusivism the contrast is made between the best, noblest adherent of some other religion versus the most crass, hypocritical, superficial adherent of Christianity. Raising your hand or praying the sinner’s prayer at camp does not automatically make you a Christian. If you are not changed and bear no fruit you have not been born again from above.
3. I am not saying that children who die at a young age, or those mentally incapable of expressing faith, cannot be saved. We know from Scripture that the Spirit can touch children in the womb (e.g., David, John the Baptist) and that the kingdom can belong to children (Mark 10:14). We see in Scripture that children from a believing household are in a different “position” than those outside the fold. They have Jesus as their covenant Lord (Eph. 6:1). When David’s son dies he says “I will go to him” (2 Sam. 12:23), this could mean “I too will die.” But in the next verse we read, “Then, David comforted his wife” (2 Sam. 12:24). I think it more likely that v. 23 was a comfort to David and Bathsheba because David knew he would see his child again in the next life. The juxtaposition of comfort makes less sense if David is simply assured he will join his son in the ground some day.
So I gladly affirm Canons of Dort, Article 1.17: “Since we must make judgments about God's will from his Word, which testifies that the children of believers are holy, not by nature but by virtue of the gracious covenant in which they together with their parents are included, godly parents ought not to doubt the election and salvation of their children whom God calls out of this life in infancy.” Beyond this, as a confessional Christian, I would not speak too dogmatically. Almost everything concerning salvation in the Bible assumes the presence of sentient human beings. Some of our other questions may not be answered directly.
4. I am not saying that unbelievers are punished because they did not put faith in a Jesus they never heard of. This may sound like the opposite of exclusivism, but it’s not. This is actually a crucial point that exclusivists and their opponents often miss. Those who never hear the gospel are not punished for not knowing Jesus. Not knowing Jesus results in punishment, but sin is the grounds for punishment. Those who do not put faith in Christ are punished for being sinners. They are punished in the next life for turning the truth of general revelation into a lie (Rom. 1:18-25). They have broken God's law, and anyone guilty of even one violation is accountable for the whole law (James 2:10). Those with no knowledge of Christ will be judged less severely because they had less light, though that judgment will still be far from painless (Matt. 11:20-24). Our only hope in life and in death is that we are not our own but belong body and soul to our faithful Savior Jesus Christ.