"What must I do to be saved?" is the most important question for which any man, woman, boy or girl of the human race desperately needs the answer. Only Jesus is excepted for He is the sinless "Son of Man (who) has come to seek and to save that which was lost" (Luke 19:10).*
But people throughout history have sought to "do" something or to refrain from "doing" something on their own to earn their salvation and to merit the "reward" of entrance into heaven. Every world religion is based upon this idea with the exception of true Christianity, which is not a religion as some classify it, but Biblical faith which results in a personal relationship with God. John 17:4 teaches us that Jesus had perfectly fulfilled all righteousness by living a sinless life - thereby accomplishing the perfection that God demanded for forgiveness of sin - "I glorified You on the earth, having accomplished the work which You have given Me to do." Everything necessary for salvation was done by this perfectly sinless substitute, Jesus, when He died in our place on the cross at Calvary. There He became the complete, final sacrifice for sin. He shed His blood, for, ". . .without shedding of blood there is no forgiveness" (Hebrews 9:22). He said, "it is finished" (John 19:30).
The question was asked of the Apostle Paul and Silas by the jailer in the prison at Philippi when he had observed their Christian testimonies and found them still there after the earthquake. They answered him, "Believe in the Lord Jesus, and you shall be saved, you and your household." (Philippians 16:29-34). The jailer believed the word of the Lord along with the other people in his house, and were saved. Their baptism did not save or help save them, but it was their testimony that they believed in the Lord Jesus as they had been instructed. God offers this gift of grace to all men in the same way it was received by the same way the jailer and his people were, "For, God so loved the world, that He gave His only begotten Son, that whoever believes in Him should not perish, but have eternal life." (John 3:16).
To believe in the Lord Jesus means simply to place one's confidence in, and to trust Him for salvation from the penalty, guilt and power of sin. It is made possible by God's grace and mercy because of His love for sinners. "For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, that no one should boast" (Ephesians 2:8-9) and, "He saved us, not on the basis of deeds which we have done in righteousness, but according to His mercy, by the washing of regeneration and renewing by the Holy Spirit" (Titus 3:5).
Everyone needs to be saved, "for all have sinned and fall short of the glory of God," and, ". . . the wages of sin is death. . ." (Romans 3:23; 6:23). This means that the unsaved are ". . .dead in (their) trespasses and sins" (Ephesians 2:1), referring to spiritual death, being separated from God. Further, in verses 4-5, the truth of spiritual resurrection is set forth: "But God, being rich in mercy, because of His great love with which He loved us, even when we were dead in our transgressions, made us alive together with Christ, (by grace you have been saved)." This points to the ultimate of salvation, for those who believe are now spiritually alive with Christ, and will be physically alive with Him eternally when He returns to take His saved ones to heaven. "Behold, I tell you a mystery; we shall not all sleep (in physical death), but we shall all be changed, in a moment, in the twinkling of an eye, at the last trumpet; for the trumpet will sound, and the dead will be raised imperishable, and we shall be changed." Also in 1 Thessalonians 4:14-17 it says that believers living at that time "shall be caught up together with them in the clouds to meet the Lord in the air, and thus we shall always be with the Lord. (v. 17). Jesus said, "I am the resurrection and the life, he who believes in Me shall live even if He dies, and everyone who lives and believes in Me shall never die." (John 11:25 - 26). Then He asks THE GREAT QUESTION, which every person must answer sooner or later, "DO YOU BELIEVE THIS ?"
I trust this helps.