Notice what else Jesus says about people who want to worship Him without obedience to God's commands: "And in vain they worship Me, teaching as doctrines the commandments of men. For laying aside the commandment of God, you hold the tradition of men. . . . All too well you reject the commandment of God, that you may keep your tradition" (Mark 7:7-9).
Man would rather do almost anything else than surrender himself to God. His natural mind (Jeremiah 17:9; Romans 8:7-8) rebels at the thought of submitting to God's law. Therefore men have substituted their own laws and customs for God's commandments, thinking they can still receive salvation by only believing in Christ as their Savior.
Human nature wants to be right, but it does not necessarily want to do right! So people often say, "Well, here's the way I look at it"—thus putting their concept of righteousness above the Bible. If it "looks right" to them, it becomes their law. This is nothing but self-righteousness. And we already know where doing what "seems right" to us will lead (Proverbs 14:12; 16:25), unless we repent of this kind of thinking.
Clearly, no amount of human works can bring about the forgiveness of sin. Even the great sacrificial laws of the Old Testament could not bring about forgiveness and a clear conscience. They were only a type looking forward to the supreme sacrifice for sins—Jesus Christ—who was to come much later (Hebrews 9:9-14; 10:4-10).
There is simply no way we can "make up" for our sins. Beads, indulgences, penance, fastings, or afflicting one's flesh in some other way will not erase the guilt of sin either. We cannot punish ourselves for sin, and thus avoid God's punishment. Only the sacrifice of Christ can pay that ultimate penalty. And the only way that sacrifice can be applied to blot out our sins is by accepting it and forsaking our past lives of disobedience—by repentance!