In Eph. 1:13 the Apostle Paul declares that men are saved and sealed by hearing and believing “the Word of truth, the gospel of your salvation.” This declaration is substantiated by many other passages of Scripture. Our Lord said: “He that heareth… and believeth… hath everlasting life” (John 5:24). This at a time when sacrifices and baptism were still required for the remission of sins. Even then men had to hear and believe to be saved, for “faith cometh by hearing, and hearing by the Word of God” (Rom. 10:17).
Now, however, salvation is received by hearing and believing alone. Works for salvation are not merely unnecessary; they are forbidden. Today salvation is “to him that worketh not, but believeth” (Rom. 4:5). “For by grace are ye saved, through faith, and that not of yourselves; it is the gift of God: not of works, lest any man should boast” (Eph. 2:8,9).
God has changed His dealings with men from time to time down through the ages, teaching one lesson at a time. This is why it is so important to note the dispensational distinctions in Scripture, “rightly dividing the Word of truth.”
Once the works of the Law were required for salvation: “But now the righteousness of God without the law is manifested” (Rom. 3:21) and men are saved solely by faith in Christ, “being justified freely by [God’s] grace, through the redemption that is in Christ Jesus” (Rom. 3:24). We are saved, then, as we hear and believe what Paul calls, “the Word of truth, the gospel of your salvation” (Eph. 1:13), and we are established in the faith as we obey II Tim. 2:15: “rightly dividing the Word of truth.” source