We are saved by faith rather than works.
Read Romans 10:1-21
"So faith comes from hearing, and hearing by the word of Christ."
Paul was deeply passionate about the salvation of the Jews. Although his ministry was to the Gentiles, he never lost his desire to see the Jews come to a saving knowledge of Christ. Part of this desire was driven by his understanding of the Jew's reliance upon works rather than faith. Paul had been zealous for the law, violently persecuting any who undermined the Old Testament law and Jewish traditions. He was present and approved of the stoning of Stephen in Acts 7:58. Paul sympathized with them in their zeal when he states, "I testify about them that they have a zeal for God, but not in accordance with knowledge" (Romans 10:2). The problem with the Jews was not their zeal but their misguided focus. The law was given so that the individual who lived by faith would be able to practice the righteousness of God (vs. 5). However, the Jews, distorting the law by seeking to use it as the basis for salvation. In so doing, they failed to recognize their inability to fulfill the law.
However, the danger of misguided zeal can easily infiltrate our lives today. In our quest to live for God, we can reduce our faith to adherence to rules and regulations. Like the Jews, we can be zealous, but our zeal can be misplaced as we focus upon external acts. We can easily forget that salvation and righteousness are not based upon what we do. Instead, it is based upon the grace of God and the redemptive work Christ accomplished on the cross. But legalism is more than just focusing upon outward performance; it goes to the heart of our desire for self-determination. Legalism is an outgrowth of our reliance upon ourselves and our abilities to bring about our salvation. It is grounded in the belief that we can be good enough to warrant our salvation and the innate desire to be the masters of our destiny.
Here is where Paul points us in a different direction. Instead of our salvation being based upon our abilities and inherent goodness, it is based solely upon the grace of God and faith in what Christ has done for us. Salvation is obtained simply by acknowledging the supremacy and deity of Christ (that is, "confess with your mouth Jesus as Lord") and trusting in what Christ accomplished on the cross when he died in our place, taking upon himself the judgment we deserved. To "believe in your heart that God raised Him from the dead" is to acknowledge that the resurrection gave conclusive testimony that Christ was God and that his redemptive work was finished. Nothing is needed on our part (see 1 Corinthians 15:1-6; 1 Peter 2:24-25). This is the simplicity of the Gospel. Salvation is attained by the simple act of surrendering to Christ and asking for him to save us from our sin (Romans 10:13). It is giving up our self-determination and instead of trusting in Christ alone.
Nevertheless, the simplicity of the Gospel is what makes it so hard to accept. In its simplicity, it requires us to surrender control and to give God control. It is to recognize that we are inherently sinful, and only he can save us from our sin. The path to righteousness is not trodden on the road of self but the road of self-denial. When we when we stop trying to earn salvation and instead accept the offer of salvation, will we truly attain the righteousness of Christ.