And at midnight Paul and Silas prayed, and sang praises unto God: and the prisoners heard them.
16:26
And suddenly there was a great earthquake, so that the foundations of the prison were shaken: and immediately all the doors were opened, and every one's bands were loosed.
16:27
And the keeper of the prison awaking out of his sleep, and seeing the prison doors open, he drew out his sword, and would have killed himself, supposing that the prisoners had been fled.
16:28
But Paul cried with a loud voice, saying, Do thyself no harm: for we are all here.
16:29
Then he called for a light, and sprang in, and came trembling, and fell down before Paul and Silas,
16:30
And brought them out, and said, Sirs, what must I do to be saved?
Authorized King James Version

This question is worthy of our examination. The question informs us of a man being lost without Christ. The jailer was no different than you and me without Christ. He was lost. Recognizing this, he asks this question. Maybe you are here today because you have the same sense of being lost. There are a lot of answers to this question, but only God gives the correct answer for he holds the authority of judgment.

I Cor. 5: 10 For we must all appear before the judgment seat of Christ; that every one may receive the things [done] in [his] body, according to that he hath done, whether [it be] good or bad.

What is God's plan of Salvation? According to the Bible one must:
Hear Acts 16:31-32 Romans 10:14; Romans 10:17

Believe: Acts 16:31; Hebrew 11:6; John 3:16

Confess: Romans 10:10; Matthew 10:32; Acts 8:37

Repent: Acts 2:37-38; II Peter 3:9; Acts 17:30

Be Baptized (immersed): Acts 22:16; Mark 16:16; Acts 2:38

The religious world today would tell you only part of the story. God has always had a plan for man. When man refuses to conform to Gods plan he does not simply break God's law, he breaks himself against His law. Have you conformed to the plan of God? Are you like the multitudes of the world and refuse water baptism. Why not take all of God's word? Nike says, "Just do it".
My encouragement to you is, "just trust and obey".