The Bible says how to be saved, and it also says how to know we are saved (a cause and effect). This can either give you assurance, or motivate you to seek God further in the way that He wants you to seek Him.
How to be saved
The Bible says we have all sinned and we are separated from God, and there is nothing we can do to bridge the gap between us and Him. So Jesus came to die for our sins and be raised from the dead, to give us eternal life. Our part is to confess our sins and trust in Him for salvation.
Personally, I grew up in church and I went along with a sinner’s prayer led by someone else when I was 6 years old. Years later, I said sinner’s prayers multiple times, but there was a problem — I still saw myself as a good person. And saying a sinner’s prayer doesn’t help if we think that we are not actually that bad. It is only an empty ritual.
In Luke 18:10–14, Jesus described the right attitude to have. A man cried out, “God, be merciful to me a sinner” and he was forgiven. It’s about being convicted of your sins and admitting that you need God’s mercy to forgive you and change you.
He doesn’t want us to point out some good things we’ve done as reasons that He should forgive us. He wants us to come admitting that we are poor. Jesus said, “blessed are the poor in spirit.” We have to put our trust in Jesus alone, not ourselves.
Romans 10 says “with the mouth confession is made unto salvation” and “whoever calls on the name of the Lord shall be saved.” Calling with your mouth- that’s like what Jesus said in the other passage about the man who called out for mercy.
So based on these verses, I believe that ideally your prayer should be out loud, as a way to express what is on your heart. Or even as a way to help it sink in, because when you hear yourself saying something out loud, it feels different from a silent thought.
When I say let it sink in, there are places in the Bible we see that concept, for example Matthew 13 where Jesus talked about the types of ground, and the good ground bears fruit.
Personally I think the truth about Jesus and myself didn’t sink in until I was 15, because that time when I prayed to trust Jesus as Savior, I immediately knew there was a change. There was no emotional experience, but something changed, and ever since then I’ve seen God working in my heart and life.
How to know you are saved
We just went through those truths about how to be saved, and it seems like it would be enough to say “I did that already” but the Bible says “We know that we are in Him by the Spirit that He has given us” (1 John 3:24) and that is the place to find assurance, by His Spirit.
Romans 8:14 says “For as many as are led by the Spirit of God, they are the sons of God” and verse 16 says His Spirit bears witness with our spirit, that we are the children of God.
Well, how do we know if we have the Spirit?
Galatians 5:22–23 says the fruit of the Spirit is love, joy, peace, etc. Those are what the Holy Spirit produces in our hearts. They are not things to strive for; we have a choice to act on those things, but that’s getting ahead; that’s after salvation, but before salvation those things were not even in our hearts; there was only emptiness.
2 Corinthians 5:17 says if any man is in Christ, he is a new creature- you’re a new creation, a new person! If you are God’s child, His Spirit is in you and you’re going to see a difference in your heart.
Now maybe you haven’t grown much outwardly, but that is different because it’s your choice to live out what God has done in your heart. It doesn’t necessarily mean you were never saved; you just need to spend time seeking God so you can grow.
However, if you’ve never had peace with God, I encourage you to seek Him right now.
Tell Him that you believe He sent Jesus to die for you. Tell Him you are sorry for your sins. Leave your own goodness behind (there is nothing good in ourselves, as the Bible says). Tell Him that you want Him to change your heart so you can be like Him- so you can truly love Him, and love and forgive others.
Be willing for Him to do that change in your heart. Ask for His Spirit. Please take time for that right now, and I believe God will give you peace and assurance.