Although some say you don't have to turn from your sin to be saved, the apostle Peter said, "Repent ... for the forgiveness of your sins"
And in Luke 13:5, Jesus Himself said, "Unless you repent, you will all likewise perish."
When Jesus sent out His disciples to proclaim the gospel, He told them to proclaim repentance for the forgiveness of sins in His name (Luke 24:47). Repentance is not something in addition to salvation. It's not a fruit of salvation. It's not a response to salvation. It's the very core of what it means to be saved.
Repentance means turning from a life of sin and turning to Jesus as Savior and Lord.
A well-known theologian once said, "The true turning of our life to God, a turning that arises from a pure and earnest fear of him; and it consists in the mortification of our flesh and of the old man, and in the vivification of the Spirit. This is something that God grants at the moment of salvation, but the believer must also practice it throughout his entire Christian life." 
Charles Spurgeon said, "I do not believe in the faith that is unaccompanied by repentance. … Repentance and faith are twins; they are born together and they will live together, and as long as a Christian is in this world, both will be needed." 
Repentance and faith are two sides of the same coin. We cannot have one without the other. Repentance is turning away from a life of sin while faith is reaching out our hand to receive God's free gift of eternal life.
If it were possible to receive salvation without repentance, then that means we're holding onto a life of sin in one hand while holding onto salvation with the other.
This reminds me of Revelation 3:16, "So, because you are lukewarm, and neither hot nor cold, I will spit you out of my mouth."
It's not possible to receive salvation without repentance because salvation without repentance is not the gospel. And repentance is not simply an intellectual change. It's not merely a change of mind, attitude, or feelings. It's a turning away from a godless way of life and turning to Christ.
But it's also important to note that we cannot do any of this on our own. We cannot repent on our own nor can we have faith in Christ on our own. Both repentance and faith are gifts from God.
Before we were saved:
- Ephesians 2:1 says we were dead in our trespasses and sins.
- Romans 3:10-11 says we were incapable of seeking after God.
- Romans 8:7 says we were unable to submit to God.
- Romans 8:8 says we were unable to please God.
- Isaiah 64:6 says all our works of righteousness were like filthy rags.
- Romans 14:23 says, since we didn't have faith, everything we did was sin.
- 1 Corinthians 2:1 says we were blinded by Satan. So, we didn't understand the things of God.
- 2 Corinthians 4:4 says, we were blinded by Satan. So, we couldn't understand the gospel.
Before Christ saved us, we were in a hopeless state. I've heard so many people say, "Yes, but I have free will to choose. I can choose Christ." We do have free will, but in our unsaved state, we'll never choose Christ on our own. We'll always choose sin.
We are dead in our trespasses and sins, incapable of seeking after God, unable to submit to Him, unable to please Him. All our works of righteousness are like filthy rags. Everything we do is sin, and we've been blinded by Satan. We don't understand the things of God or the gospel.
Yes, we have free will, but apart for Christ, we'll choose sin over Christ every single time.
Repentance (2 Timothy 2:25) and faith (Ephesians 2:8) are gifts from God. Without God intervening in our lives, no one would be saved. Without God giving us the gifts of repentance and faith, no one would be saved. Because repentance and faith are gracious and merciful gifts of God, our salvation is completely the work of God.
Without repentance we will never see Jesus for who He is. When Peter preached his sermon to about 10,000 Jews at Pentecost, he showed them several things:
- Jesus fulfilled the Old Testament prophecies about the Messiah.
- Jesus is the Holy and Righteous One (3:14).
- Jesus rose from the dead (3:15).
When the Jews saw that Jesus is the Messiah, the Holy One sent by God, and had risen from the dead, they asked the apostles, "Brothers, what shall we do?"
To which Peter replied, "Repent."
In order for anyone to be saved, they must realize who Jesus is: God in the flesh, who came to die on the cross to pay for the sins of all who would believe in Him. He saved us from the just wrath we deserved. The only way anyone can see Christ for who He truly is, is if God brings them to repentance.
The only reason we will repent is if God causes us to recognize our sinfulness and need of forgiveness.
After Peter delivered his sermon, verse 37 says, "Now when they heard this they were cut to the heart." Convicting the heart of sinners is a work of the Holy Spirit.
Before Christ came to earth, we were all blinded by the god of this world from seeing the light of the gospel (2 Corinthians 4:4). Because of that, we don't recognize our fallen state and we don't think we need a savior.
Many people believe if their good deeds outweigh their bad ones, they'll go to heaven—if it is actually a real place. They compare themselves to murders and thieves and child abusers and feel confident that those are the types of people who deserve to go to hell.
But God doesn't judge people based on how relatively good they are. He judges them by His perfect holiness (Matthew 5:48). And since we're not as perfect and holy as He is, we rightly deserve His just wrath.
Apart from God, the best a person can do is look at their life and make a few moral adjustments, but that's it. Only God can cut to the heart. Only He can change our heart. Only He can give us new life. Only He can change us from the inside out.
We must repent. Plus, to receive God's forgiveness, we must faithfully believe in Jesus Christ.
Although John 10:28 and several other passages teach eternal security, salvation is not a one-time decision for Christ that doesn't make a lasting impact on our life. Salvation is a total surrender to Jesus Christ.
Leading up to and at the time of our salvation, the Holy Spirit does the following:
- Replace our heart of stone with a heart of flesh.
- Give us the gift of repentance.
- Convict us of our sin.
- Give us the gift of faith.
- Remove the veil over our eyes.
- Reveal the glory of God.
- Seal our salvation, making it permanent.
- Give us spiritual gifts, unique to the call God has for us.
- Take up permanent residence within us.
At salvation, we become new. We're no longer dead, but alive. We break free from the bondage of sin and Satan. We're no longer part of this wicked generation. Instead, we're radically different, set apart as a beacon of God's glory, shining in this dark world. If a person claims to be saved, yet their life doesn't reflect the work of the Holy Spirit, they might not be saved at all.
Even though the Holy Spirit made us new, we're still sinners. We're not perfect. We still struggle with sin and sometimes go further than we want to go. However, the general direction of a believer's life will be to increasingly please the Lord.
Second Corinthians 13:5 instructs us to "examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?—unless indeed you fail to meet the test!" If a person claims to be a Christian, but their life displays continual disobedience to God, then they need to question whether they truly believe.
If we repent of our sin and faithfully believe, Peter tells us we are to be baptized. When we think of baptism, we usually think of two things, the physical act of being immersed in water and what it represents spiritually.
Romans 6:4 says, "We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life."
Baptism also had cultural implications for Peter's Jewish audience. They would have been shocked to hear that they were to be baptized. Only Gentiles who were converting to Judaism were baptized at that time. When Peter called the Jews to be baptized, he was calling them to radically break free from the world and identify with Christ.
Salvation is a personal matter between us and God. It doesn't matter if we've been raised in the church and know all the churchy terms, married a Christian, had kids and raised them in church. None of that saves us. Peter encourages his audience, and us, that the only way anyone can receive forgiveness for their sins is to repent of our sins and trust in Christ alone. We must keep short accounts with God, not as if we might lose our salvation, but as a means of growing closer to Christ.
When John wrote his epistles, he was writing to believers. They were people who had already repented of their sins and trusted in Christ for salvation. Yet, in 1 John 1:9, he said, "If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness." Confess
is in the present tense. We should keep confessing our sin. We should keep on repenting. Repentance isn't a one-time, once-for-all event. Instead, we're to repent daily. Our daily sin is a hindrance to our fellowship with the Lord.
If you haven't repented and come to saving faith, I encourage you to ask the Lord to lead you into the truth of the gospel.
If you have, I encourage you to keep short accounts with God and grow in your relationship with Him.
 John Calvin - Calvin's Institutes, 3:3:5; 3:3:9
 Metropolitan Tabernacle Pulpit [Ages Software], vol. 54, "Heart-piercing," Acts 2:37