The simple answer is that salvation by works seems right in the eyes of man. One of man’s basic desires is to be in control of his own destiny, and that includes his eternal destiny. Salvation by works appeals to man’s pride and his desire to be in control. Being saved by works appeals to that desire far more than the idea of being saved by faith alone. Also, man has an inherent sense of justice. Even the most ardent atheist believes in some type of justice and has a sense of right and wrong, even if he has no moral basis for making such judgments. Our inherent sense of right and wrong demands that if we are to be saved, our “good works” must outweigh our “bad works.” Therefore it is natural that when man creates a religion it would involve some type of salvation by works.
Because salvation by works appeals to man’s sinful nature, it forms the basis of almost every religion except for biblical Christianity.Proverbs 14:12 tells us that: “There is a way that seems right to a man, but its end is the way of death.” Salvation by works seems right to men, which is why it is the predominantly held viewpoint. That is exactly why biblical Christianity is so different from all other religions—it is the only religion that teaches salvation is a gift of God and not of works. “For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God—not by works, so that no one can boast” (Ephesians 2:8-9).
Read more: http://www.gotquestions.org/salvation-by-works.html