"Your Own Salvation"
No doubt most folks reading articles found in the bulletin of a church of Christ are aware of some of the false teachings regarding salvation that are reviewed. What springs to mind are misconceptions associated with how our souls can be saved. Many claim that you need only "accept Jesus into your life as your personal savior" in order that you may enter the kingdom of heaven. Some say you must confess every sin you've ever committed to a special clergyman and cancel out said sin by saying, "Hail Mary," repeatedly. Others claim that one must say the "sinner's prayer," and that alone is sufficient to save one's soul. It would take a rather large volume, or several, to cover every false plan of salvation contrived by men.
On and on the list could go, but what's something that every method on this hypothetical list would have in common? None of them are found in the Bible, which is God's inspired Word. It, and only it, contains the instructions necessary for remission of sins. Another thing that every item on that list has in common; or (more appropriately), something that every originator of the false teachings on that list has in common is that they are, all of them, whether consciously or unconsciously, convinced that they can devise their own means of salvation. They are guilty of the same kind of pride that Jesus mentioned concerning the Pharisees.
The Pharisee stood and prayed thus with himself, "God, I thank You that I am not like other men—extortioners, unjust, adulterers, or even as this tax collector. I fast twice a week; I give tithes of all that I possess." And the tax collector, standing afar off, would not so much as raise his eyes to heaven, but beat his breast, saying, "God, be merciful to me a sinner!" (Luke 18:11-13).
Think about the inordinate gall of this man—to make a prayer to God Himself, but not humbly giving thanks or begging for mercy; instead, he made overtures about his own righteousness, acting as if he was the greatest thing since sliced cheese. On top of that, the Pharisee went out of his way to insult his fellow man who was there making a proper supplication to the Lord. What's darkly comedic about this scenario is that he believes it is appropriate to do so. This man sincerely believed that he was justified in making such remarks; he truly thought that his self-righteousness was impressive to God.
This presumptuousness was not exclusive to this lone Pharisee; it is characteristic of most of the Pharisees, Sadducees, and scribes mentioned in the New Testament. They were binding their own traditions as doctrines of God (Mark 7:6-7) and simultaneously disregarding the more prominent commandments of the Law of Moses (Matt. 23:23-24).
Are not those who twist God's plan of salvation, or fabricate an entirely new plan of salvation, guilty of precisely the same presumptuousness of those whom both John the Baptizer and Jesus the Christ referred to as "brood of vipers" (Matt. 3:7, 23:33)? The wickedness of the scribes and Pharisees kept not only them from entering the kingdom of heaven, but also many of their fellow Jews (Matt. 23:13). Is not that also true of the sort of Biblical "scholars" and "pastors" in the past two millennia (and still today) who insist that salvation may be attained by some means other than what is written by the inspired writers?
Just as with the Jews before the crucifixion, so too was it with the Christians following Christ's ascension. Many of the letters written by Paul were critical in nature. They consisted predominantly of his attempts to convince straying churches to return to the doctrine that the apostles delivered to them. It is evident, therefore, that everyone seeking Christ must conform to that doctrine, whether in the 1st century, or the 21st.
Working Out Your Own Salvation
If keeping His commandments didn't matter, and if man could add, change, or modify the means by which he obtains salvation, then why did Paul (and others) go to such great lengths to correct erring disciples? They certainly were not writing epistles that stated (explicitly or implicitly) there were multiple sects of Christianity and that they were all equivalent in their capacity to save men's souls. Consider what Paul told the Philippians:
Therefore, my beloved, as you have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling; for it is God who works in you both to will and to do for His good pleasure (Phil. 2:12-13).
What does the phrase, work out your own salvation, mean? If that was the only thing Paul said, then maybe false teachers would have a point: We could just come up with our own plan of salvation, and each would be just as valid as another. But that is very obviously not what Paul is saying. The immediate context, both in those two verses and the entire epistle, completely contradicts that idea. Paul just said (in other words): "You obeyed the doctrine I delivered to you while I was with you, and since I'm no longer there in person, you need to be even more diligent to stick to it, because that is what God expects of you."
That message was true for the Philippians and remains true for us. To work out one's own salvation is to seek first the kingdom of God for oneself, and to do so according to His will, not one's own. The comment about false teachers having a point was tongue-in-cheek, because, even if the immediate context didn't provide the nuance that it does, the remote context wouldn't jive with that out-of-context quote either. Nowhere in Matthew, Mark, Luke, John, Acts, or the epistles is there any provision given for the disciples to make modifications to God's doctrine and slap a new name on His church (Catholic, Baptist, Pentecostal, Mormon, et al.). Paul rather pointedly refutes such a thing in Galatians 1:8-9.
But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed.
As we have said before, so now I say again, if any one preaches any other gospel to you than what you have received, let him be accursed.
Anyone that claims the name of Christian ought to regard with the utmost diligence, more than in any other aspect of life, their service to God. That means each individual must gain an understanding of His will in order that he may carry it out properly. It is not for us to determine what the criteria for salvation are. It is not for us to add to or take away from the gospel. It is ours to study and then apply the Word of God as He delivered it.
Jesus gave the apostles the authority to loose the Law of Moses and bind the Law of Christ (Matt. 16:19), and so they did by the inspiration of the Holy Spirit (Acts 1:8). And that is why, after the first 3,000 converts were told on the Day of Pentecost that they needed to repent and be baptized for the remission of sins (Acts 2:38), they continued steadfastly in the apostles' doctrine (v. 42)—not anyone else's, not their own, not a modified version—the apostles' doctrine.
No one was ever given the same authority that Jesus gave them in Matthew 16, and it is not necessary that anyone else be given such authority. Christianity "…was once for all delivered to the saints" (Jude 3). God's will is laid out in the Scripture. Any deviation from it is a tradition of men, which will have the same result today as it did for the scribes and Pharisees: the kingdom of heaven was shut to them, and to their followers (Matt. 23:13). Long since written is the proper attitude of a servant of God: "O Lord, I know the way of man is not in himself; it is not in man who walks to direct his own steps" (Jer. 10:23).