The following is an excerpt from The MacArthur New Testament Commentary on Acts 16.

After he brought them out, he said, “Sirs, what must I do to be saved?” And they said, “Believe in the Lord Jesus, and you shall be saved, you and your household.” And they spoke the word of the Lord to him together with all who were in his house. (Acts 16:30–32)

No doubt having first made sure the other prisoners were secure, the jailer brought Paul and Silas out into the courtyard. There he asked the question that was burning in his heart, “Sirs, what must I do to be saved?” Some have interpreted his question in terms of being saved from punishment, but that is not the case. Since no prisoners had escaped, he faced no punishment from his superiors. And why ask two prisoners such a question? The jailer’s question expressed the deep longing of his heart to be right with God. Having undoubtedly heard the testimony of the demon-possessed girl (v. 17), either in person or from others, he believed Paul and Silas had the answer.

To the jailer’s simple and direct question the missionaries gave an equally simple and direct answer: “Believe in the Lord Jesus, and you shall be saved.” Unlike the rich young ruler (Luke 18:18–23), his heart was ready; nothing stood in his way.

The truth that salvation is wholly by faith in the Lord Jesus Christ permeates the Scriptures. “There is salvation in no one else,” according to Acts 4:12, “for there is no other name under heaven that has been given among men, by which we must be saved.” That glorious truth was at the heart of apostolic preaching (see also Acts 2:38–39; 5:14; 8:12). Jesus Himself declared, “I am the way, and the truth, and the life; no one comes to the Father, but through Me” (John 14:6). It is also the constant theme of the epistles (cf. Rom. 3:20–25; 5:1; 1 Cor. 6:11; Gal. 2:16; 3:24; Eph. 2:8–9).

To believe in the Lord Jesus means first to believe He is who He claimed to be. The apostle John wrote, “These have been written that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name” (John 20:31). Second, it means to believe in what He did. Paul succinctly summarized the work of Christ in 1 Corinthians 15:3–4:

For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures.

To the Romans he wrote:

If you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you shall be saved; for with the heart man believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation. (Rom. 10:9–10)

The message of salvation was preached not to the jailer alone but also to the rest of his household. Accordingly, the two missionaries spoke the word of the Lord to him together with all who were in his house. His family, servants, and perhaps relatives or guests who were staying with him all heard the gospel (cf. v. 15; Acts 11:14; 18:8). That the others in the jailer’s household individually believed the gospel becomes clear in v. 34 (cf. Acts 10:44).