Romans 10:9

because [the gospel (and Moses) speak of the mouth and heart, because] if thou shalt confess with thy mouth Jesus as Lord, and shalt believe in thy heart that God raised him from the dead, thou shalt be saved [Moses emphasized the nearness of the law. The Jew was to keep it near (accept it), for, as a far-off, neglected thing, it would be of no avail. As an accepted rule, loved and talked over daily, it would be effective unto righteousness. Jeremiah, foretelling the days when a new law would be more effective than the old, declared that the promise of Jehovah was: "I will put my law in their inward parts, and in their hearts will I write it." Thus it would become nearer than when written externally upon stone. When this new law came, Jesus indicated the fulfillment of Jeremiah's word by saying. "The kingdom of God is within you" (Jeremiah 31:33; Luke 17:20). Therefore, when Paul quotes Moses' words about that nearness of the law which makes it effective, he takes occasion to describe how the gospel or "word of faith" is made effective unto righteousness by the believer's full consent to the will of God that it be near him, making it an inward nearness by confession with the mouth and belief in the heart. In short, the gospel is not righteousness unto life until it is accepted, and the prescribed method by which it is to be accepted is faith leading to confession, followed by obedience of faith, beginning with baptism, which symbolically unites us with our Lord in his death and resurrection. But Paul makes no reference to the ordinance, laying stress on the central truth of Christianity which the ordinance shows forth; namely, God raised Jesus from the dead. The zealous lover of first principles might expect Paul to make the Christhood of Jesus the object of belief (Matthew 16:16). But that is already taken care of by the apostle in the brief summary: "Confess with thy mouth Jesus as Lord." The truth is, the resurrection is the demonstration of that proposition: "Jesus is the Christ, the Son of the living God." "Jesus" means "Saviour," and the resurrection proves or demonstrates his ability to save from death and the grave (1 Corinthians 15:12-19; 1 Peter 1:3-5; 2 Corinthians 4:14). Jesus is Christ; that is, God's anointed Prophet, Priest and King over all men; for such is the meaning of "Christ." Now, the resurrection proves that Jesus was a teacher of truth, for God honors no liars with a resurrection like that of Jesus; it proves that lie is an acceptable High Priest, for had not his offering for sin canceled the guilt of sin, he had appeared no more in the land of the living (Matthew 5:26), but he was raised to complete his priestly work for our justification (see note on Romans 4:25; and Acts 13:37-39); it demonstrated that he was the King, for by his resurrection he led captivity captive (Ephesians 4:8) and received the gift of universal power (Matthew 28:18; Acts 2:23-36; Acts 13:34-37; Acts 17:31; Philippians 2:8-11; Ephesians 1:19-23); and, finally, it declared him to be the Son of God with power-- Romans 1:4; Acts 13:32-33]: