God's complaint against Israel's religion is that it had form but no substance. The people made pilgrimages to their shrines, but they did not grieve for their nation's sins (Amos 6:6). They went to church, but they continued to cheat and steal and lie (Amos 8:5-6). They made a great show of being religious, but their religion caused no changes in their conduct.
God's Word shows that true religion is having concern for and helping the weak, as well as showing hospitality and generosity to those who cannot return the favor (James 1:27). It is sacrificing oneself in service; as Christ said, "Greater love has no one than this, than to lay down one's life for his friends" (John 15:13). It is speaking the truth and being honest—even swearing to one's own hurt (Psalm 15:4)—not backbiting or gossiping. True religion is not exacting the last cent on a deal, or impatiently watching the sun go down on the Sabbath to do one's business or pleasure. It is not taking usury and so on. To use a cliché, Israel talked the talk but did not walk the walk.
Even after giving them His law, God did not leave the people of Israel without a witness—a right example—of how to live. While they were drifting away, He gave them the Nazirites, people who had consecrated themselves to God (Amos 2:11; see Numbers 6:1-21). A Nazirite, a "separated one," was anyone from a tribe other than Levi who dedicated himself to God for a special period of time. Nazirites were separate because of their holiness; they vowed not to drink wine, cut their hair, or touch dead bodies.
God apparently called enough Nazirites within Israel to exemplify pure living before His people. Additionally, He sent prophets to testify against the nation and expose the direction she was going. How did Israel react? Probably through some kind of persecution, they forced the Nazirites to break their vow and muzzled the prophets (Amos 2:12).
The more holy we become, the greater the contrast between us and the world—and the more likely the world will seek to persecute us. When Jesus Christ, the most holy, moral, and different human being who ever lived, walked this earth, His own people killed Him. They could not tolerate His holiness. Thus, He warned His disciples, "If they persecuted Me, they will also persecute you" (John 15:20).