As I see it there are two related reasons why persons would convey such a thought. One is the nature of man, and the other is being motivated by a legalistic, sectarian mind, and as I have indicated the two are related. The nature of fallen man is to put the emphasis upon self. He is arrogant, proud, and self-righteous. Those believers caught up in legalism and the party spirit tend to convey these same characteristics.
The legalistic, sectarian imbued believer is law-oriented and sees his interpretations and practices as the way of salvation. If you want to be saved, conform to my thoughts and ways. I am at the top of the totem pole when it comers to authority, faithfulness, knowledge, loyalty, and soundness. Trust me and what I say.
The legalistic, sectarian is suspicious of grace and love and has built a theology that limits the role of grace and denigrates the meaning of the death of Christ. He makes works determinative of salvation rather than indicative. Is it any wonder that the apostle Paul was outraged when he learned that some in Galatia were teaching that justification is by keeping works of law?
I think there are many sheep in the fold caught up in this legalistic, sectarian theology through ignorance. I think there are a number of leaders who convey, promote, and propagandize this theology who should know better and do differently. The bottom line is that we do not save ourselves, or others, for we are too sinful and weak to attain salvation that way. We need to throw ourselves down before the throne of grace, thank God, and trust Jesus Christ. Ultimately God will judge us all, and who wants to appear before Him with a heart that says I trusted myself and my works to be saved, and so taught others, rather than having a heart fully surrendered and trusting in Jesus Christ?