Salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved.
This verse, coupled with Romans 10:14-15, is a pretty air-tight case that unless someone hears and believes the gospel of Jesus Christ, they are doomed to spend eternity seperated from God in hell. There is certainly more evidence for such a position than this, but it's a good starting place.
The reason that I spent such a great deal of time emphasizing the exclusivity of gospel is twofold. First, it demonstrates the glory of Christ. Secondly, it unveils the absolute wickedness and depravity of man. I find this teaching especially helpful to illustrate the latter.
Typically, when I preach this point, I tell the listeners about "Joe Pagan." Joe Pagan is a guy who lives in India who has never heard the gospel. Despite our efforts, he has managed to be gospel ignorant for his entire life. I then inform the listeners that when Joe Pagan dies, he spends his eternity in hell.
Most of the time, this statement is met with a sense of indignation in the hearers, if not outright horror. I have found that Christians strenously object to this verdict. Typically, the objection centers on the "unfairness" of such a verdict. That is, it is unfair to Joe Pagan because he never had a "chance" to hear and believe the gospel.
This is an excellent objection and a grand opportunity for teaching. The objection reveals a fundamental misunderstanding of human sinfulness and God's grace. The objection assumes that because God saves some, He owes everyone an opportunity for salvation. The problem with this is that if God owes someone something, then it is not, by definition, grace! You cannot have the gospel be a gracious offer while simultaneously being an offer that He is indebted to give. God owes no one any "chance" of salvation.
It demonstrates a lack of knowledge about human sinfulness in that it simply ignores the Scriptural teaching about how bad we really are. I believe that Romans 3:10-18 by itself underscores this truth. I quote it here for our humility:
There is no one righteous, not even one: there is no one who understands, no one who seeks God. All have turned away, they have together become worthless; there is no one who does good, not even one. Their throats are open graves; their tongues practice deceit. The poison of vipers is on their lips. Their mouths are full of cursing and bitterness. Their feet are sweift to shed blood; ruin and misery mark their ways, and the way of peace they do not know. There is no fear of God before their eyes.
What this means is that Joe Pagan is evil. He hates God, and he lives unrighteously. Indeed, Paul spends the better part of Romans 1-3 binding the entire world under the condemnation of sin. All men suppress the knowledge of God, refuse the light of God, and hate God with all of their might unless God does a miraculous intervention.
So, if Joe Pagan goes to hell without hearing the gospel, it is because he deserves to there. Period. Just like you did. And it is not luck that seperates you from Joe Pagan; it is grace. For some mysterious reason, God's pleasure was moved to share with you the life-giving truth about the forgiveness of sins through His only-begotten Son. Woe be to us if we neglect so great a salvation that some ears never hear!
The thing that I want my Church to think about through this teaching is the utter depravity and sinfulness of mankind. If they can leave this section of Scripture knowing that Joe Pagan deserves hell, then they have a better understanding of the grace of God in their lives. There is much more that can be added to this, such as the necessity for fulfilling the Great Comission.
I shudder to think that there are Christians who deny the fundamental truths discussed here. It is detrimental to the Great Commission, and it is an insult to Jesus Christ and His church.