rd:
He told him the truth. The jailer obviously already believed or he wouldn't have asked the question.
Well, the Jailor had not yet heard the word of the Lord when he asked the question, that came after words Acts 16:
30And brought them out, and said, Sirs, what must I do to be saved?
31And they said, Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house.
32And
they spake unto him the word of the Lord, and to all that were in his house.
Faith cometh by hearing the word of God. Now, I believe the Jailor was born again when he asked the question. And notice how its worded,
"what must I do to be saved " Not what must I do to get saved !
And Paul answered him in like fashion, Gave him a imperative and stated, believe on the Lord and thou shalt be saved, again not get saved. Both times saved is in the passive voice.
Now, how was he to believe on the Lord if he had not yet heard the Gospel ? So they spake unto him and his family the word of the Lord, that is they explained the Person and work of Jesus Christ to them, who He was, what He had accomplished, and for whom He accomplished it.
Now Paul taught that it was by the obedience of one, that many shall be made righteous Rom 5:19b
so by the
obedience of one shall many be made righteous.
The obedience here is talking about Christ death on the cross Phil 2:
8And being found in fashion as a man, he humbled himself,
and became obedient unto death, even the death of the cross.
I am sure paul preached to him the obedience of the cross, and the fruit or accomplishment of it, that many shall be made righteous, by His one act of obedience.
Now, If the Jailor believed, he would have believed that he had been made righteous by Christ obedience, the Spirit would have witnessed or testified to his spirit with the word of the Lord. Now if that be the case, his believing was not a conditioned he fulfilled to get saved, but an embracing of the fact he had been made righteous by Christ death of obedience, so his believing gave evidence of being in a saved or Justified state before God, Why ? Because of the obedience of one.. Hence believing is not a condition to get saved, but an evidence of having been saved or made righteous by Christ blood.