οι δε ειπαν πιστευσον επι τον κυριον ιησουν και σωθηση συ και ο οικος σου
The word of focus here is: πιστευσον
The word here is in the AORIST, ACTIVE, IMPERATIVE
Here is what that means- it is a punctiliar action done NOW.
The word means to believe, to entrust, to place your trust in.
So what is this belief and what isn't this belief?
1. It is not to only believe facts or information about. For example, if you believe that Jesus is the Lord, God, the only savior, died on the cross, and rose again- that belief, while accurate, will not save you.
James 2:19- "You believe that there is one God. Good! Even the demons believe that--and shudder." So a mere believe in facts...to say that these things are true....they don't amount to you being saved.
2. Belief is TRUST. The Greek word pisteuo has to do with belief in, having faith in, trusting in.
No doubt, in this scene in Acts 16, the jailer believed that there was something about Jesus. He realized that something more had to happen though. He was convinced that Jesus was Lord, and that Jesus was sovereign. But now what? The context is one that begs to come under Jesus.
John 3:16- "For God so loved the world that he gave his only begotten son, that whosoever BELIEVES in him will not perish but have everlasting life."
Believes here is the same Greek word- but is in the present active- you are the one doing the work of believing and it is a current and ongoing process.
One example from daily life is a chair. You can believe all day long that it can hold you up. But until you sit in that chair you are not trusting that chair. So it is with Jesus. You can believe facts about him all day long, but you are not safe until you trust in him by placing your life and hope in him.
3. Belief is ACTIVE.
Someone just asked me if you need to repent to be saved. While that is true, it is hard to answer that question, because of the possible ways they may understand the word repent. Do they mean that they just believe in facts about Jesus and continue in their sin? Do they mean that they need to trust Jesus and then not trust him with their lives and hope? The second makes no sense. The first is what most unredeemed people do anyhow.
Well Jesus said in Mark 1:15- "The time is fulfilled and the kingdom of God is at hand; therefore repent and believe the good news."
So, seeing that belief is active trust in Jesus and since we are called to repent by Jesus, then YES repentance is necessary for salvation. Someone cannot place their trust in Jesus yet not trust him. This is not a biblical understanding of faith, belief, trust. This is a secular view of those words.
Repentance happens to someone who places their trust from one thing into the hands of another. In fact, the word for repentance means to turn. You are turning from sitting in one chair (say the Joe chair), getting up, turning, and placing your weight in the Jesus chair instead.
To say, I believe in this chair but I will not, I don't have to sit in it....what good is that belief? What does that belief get you? Nothing.
Back to the original verse-
"Believe in the Lord Jesus and you will be saved."
Believe (to place your trust in) is active (you are believing, you are moving your trust) it includes repentance (a change of direction, a new dependence, a new direction), and continues.
So, have you gotten to a point where you have said, I have had enough. This isn't getting me anywhere. My life, to this point, has been pretty empty. And if I were to die, what would happen to me? Where would I go?
Have you looked at Jesus and thought, you died on the cross for me, you are the Lord, you are obviously my only hope.
Have you said, "Jesus I want you to save me. I am placing my hope, placing my trust in you. You are my rock, my safety. I will trust you."?
And have you finally quit trusting in your own efforts and have decided to trust His very capable hands? Have you taken him as your savior?