Repentance is sadly missing today in our churches or it is misunderstood.
Without repentance our faith is not a real faith.
Our baptism is not a real baptism and our salvation is not a real salvation.
It all starts with repentance.

This was the first words that came out of Jesus' mouth. Saying that we should preach this to the whole world.
First repentance and then faith in God.

See this video where Torben Søndergaard and Jon Bjarnastein talks about the importance of repentance and what true repentance is.

Luk 24:46 He told them, "This is what is written: The Messiah will suffer and rise from the dead on the third day,
Luk 24:47 and repentance for the forgiveness of sins will be preached in his name to all nations, beginning at Jerusalem.

Acts 2.38
38 And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.

1 John 3
4 Everyone who sins is breaking God’s law, for all sin is contrary to the law of God. 5 And you know that Jesus came to take away our sins, and there is no sin in him. 6 Anyone who continues to live in him will not sin. But anyone who keeps on sinning does not know him or understand who he is.
7 Dear children, don’t let anyone deceive you about this: When people do what is right, it shows that they are righteous, even as Christ is righteous. 8 But when people keep on sinning, it shows that they belong to the devil, who has been sinning since the beginning. But the Son of God came to destroy the works of the devil. 9 Those who have been born into God’s family do not make a practice of sinning, because God’s life is in them. So they can’t keep on sinning, because they are children of God. 10 So now we can tell who are children of God and who are children of the devil. Anyone who does not live righteously and does not love other believers[b] does not belong to God.