The Bible is clear that apart from Christ, you can't be saved. Jesus said, "No one comes to the Father except through me" (John 14:6).
But what about people who have never heard the gospel? Maybe they live in some remote tribe or region where there are no missionaries.
God’s Word says,
"They know the truth about God because he has made it obvious to them. For ever since the world was created, people have seen the earth and sky. Through everything God made, they can clearly see his invisible qualities—his eternal power and divine nature. So they have no excuse for not knowing God." (Romans 1:19-20, New Living Translation).
Nature itself is a witness to the true God and Creator. We can see what He has made. There is no excuse for not knowing God as the Creator.
Ideally the witness of God through His creation would lead a person to a true knowledge of Him. But because we are all fallen and sinful, we inevitably twist that natural revelation and come up with the wrong conclusions,
“Yes, they knew God, but they wouldn’t worship him as God or even give him thanks. And they began to think up foolish ideas of what God was like. As a result, their minds became dark and confused. Claiming to be wise, they instead became utter fools. And instead of worshiping the glorious, ever-living God, they worshiped idols made to look like mere people and birds and animals and reptiles.” (Romans 1:21-23, New Living Translation)
So the witness to God from Creation points to the true God, but before we put our faith in Christ as our Savior, we “were dead in our trespasses and sins” (Ephesians 2:1). A dead man can’t move toward God!
A similar question is asked, “But what if someone lives up to the light they have? Will God save them?” From Romans 1:21-23 it says that in fact no one actually does live up to that light. Not on their own. God would have to move first to open their eyes and heart (John 6:44). It’s exactly the same for those who live in America where the gospel is everywhere. So, if we do see someone truly reaching out to the true God, whether they live in Atlanta or the remote Amazon, we can be sure that God is at work and as He did with Cornelius (Acts 10) He will make sure they hear the gospel by some means. This is why Jesus commanded believers to “Go, therefore, and make disciples of all the nations” (Matt 29:19-20).