The Philippian jailer asked Paul and Silas, “Sirs, what must I do to be saved?” And they said, “Believe on the Lord Jesus Christ and you will be saved…” (Acts 16:30-31).
Other people provide more complex answers to this question. Some put a high value on repentance of sin. Others insist that since “faith without works is dead” (James 2:17) if you don’t have the right kind of works it can’t be that you have the right kind of faith. Still others emphasize Jesus’ own teaching from His Sermon on the Mount: “On that day many will say to Me, ‘Lord, Lord did we not prophesy in Your name, and cast out demons in Your name, and do many mighty works in Your name?’ And then I will declare to them, ‘I never knew you; depart from Me, you workers of lawlessness’” (Matt. 7:22-23).
The purpose of using Acts 16:31 as a key, “how do I get saved?” passage is: 1) Paul and Silas are answering just that question, and 2) they provide the most basic answer possible in their response: believe and you will be saved. Belief is important.
One of the main reasons that belief (and this passage) matters so much is because it can provide undoubtable assurance to a believer in the midst of his life. I have heard it said that the Bible does not guarantee any assurance of salvation to a person living in sin. This is not true. Every individual who has ever put his faith alone in Christ alone can have complete assurance regardless of the life he lives. Not that he should live an immoral life, just that one’s works cannot provide irrefutable assurance. Assurance is based on the promises of God in His word, the Bible.
The problem isn’t that sinning Christians shouldn’t reconsider their life and seek to change it; the problem is with Christians (or non-Christian) who aren’t obviously sinning who begin to think their moral life proves their salvation. “I guess I am a pretty good fella after all. How could God reject such a nice fella like me?” In fact that seems to be the type of people Jesus references in Matthew 7. “Lord, look at all the great stuff I’ve done!”
A thought experiment might help. Imagine the Rapture happens. The Rapture is the belief that at some point Jesus will return and take away all those who have passed away having trusted in Him and all those alive who have trusted in Him. He will take them to Himself where they will be judged according to their works in order to receive rewards for the Kingdom and the eternal state. At the Rapture, those who are alive but have not trusted in Christ remain on earth and will endure a period of terrible suffering called the Tribulation. This will end when Christ returns with His judged/rewarded bride and establishes His kingdom. Non-believers are judged separately following a thousand year Kingdom where Christ rules and reigns from the throne of David in Jerusalem.
Now imagine one of the left behind individuals who had grown up in church, attempted to live a moral life, had done innumerable good works (certainly more good than bad!). Now, he’s traversing through the tribulation! What went wrong? “I know that faith without works is dead and look at all my works! Haven’t I done so many wonderful things? Why was I left behind?” For him the solution could only be to try to do more good works so that God would spare him at the next judgment that takes place (the sheep and goat judgment at the end of the Tribulation). In other words based on what he had learned he would think that he failed to merit forgiveness which, from the Christian viewpoint, is based on grace (unmerited favor given by God to man on the basis of the work of Jesus Christ), because he didn’t have works. He didn’t have enough merit to merit an unmerited gift.
Now let’s turn to the Philippian jailer. Imagine him remaining after the Rapture. Paul and Silas had told him that in order to be saved he must believe on the Lord Jesus Christ. Certainly that message included additional content related to Who Jesus Christ is (it wouldn’t be Jesus Christ the physician’s assistant who lives next door, for example), and what Jesus did. Jesus Christ is the eternal Son of God. He died on the cross paying the penalty for every single sin in human history. He was buried and on the third day He rose again. Knowing that, having believed that, what could the left behind jailer do? Believe harder? What would that look like? Believe until it sticks? How many times would it take to take?
On the one hand, we have a viewpoint that insists that works isn’t the issue then goes on to make works the precise issue. On the other hand, we have a viewpoint that makes one’s faith alone in Christ alone, one’s belief concerning Jesus, the entire issue as it concerns one’s eternal destiny. It is impossible to know if one has done enough good works to prove he has the right kind of faith. But one can know if He believes in the One Who raises the dead by simply thinking, “What do I believe?” What do you believe?
Jesus said to Martha, “I am the resurrection and the life. Whoever believes in Me, though he die, yet shall he live, and everyone who lives and believes in Me shall never die. Do you believe this?” (John 11:25-26).