(Mat 4:17 KJV) From that time Jesus began to preach, and to say, Repent: for the kingdom of heaven is at hand.
Biblical repentance is admitting one sins to God, stopping and consciously turning away from them, turning back toward God, and personally accepting Jesus Christ finished work, forgiveness for them. True repentance is confession, contrition, change; replacement and it involves the whole person, Our Body, Soul, Spirit. It is also a personal, ongoing event.
Luke 24:33 And they rose up the same hour, and returned to Jerusalem, and found the eleven gathered together, and them that were with them, Luke 24:34 Saying, The Lord is risen indeed, and hath appeared to Simon. Luke 24:35 And they told what things were done in the way, and how he was known of them in breaking of bread. Luke 24:36 And as they thus spake, Jesus himself stood in the midst of them, and saith unto them, Peace be unto you. Luke 24:37 But they were terrified and affrighted, and supposed that they had seen a spirit. Luke 24:38 And he said unto them, Why are ye troubled? and why do thoughts arise in your hearts? Luke 24:39 Behold my hands and my feet, that it is I myself: handle me, and see; for a spirit hath not flesh and bones, as ye see me have. Luke 24:40 And when he had thus spoken, he showed them his hands and his feet. Luke 24:41 And while they yet believed not for joy, and wondered, he said unto them, Have ye here any meat? Luke 24:42 And they gave him a piece of a broiled fish, and of an honeycomb. Luke 24:43 And he took it, and did eat before them. Luke 24:44 And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me. Luke 24:45 Then opened he their understanding, that they might understand the scriptures, Luke 24:46 And said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day: Luke 24:47 And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem. Luke 24:48 And ye are witnesses of these things. Luke 24:49 And, behold, I send the promise of my Father upon you: but tarry ye in the city of Jerusalem, until ye be endued with power from on high.
(Rev 2:5 KJV) Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent.
(Rev 2:16 KJV) Repent; or else I will come unto thee quickly, and will fight against them with the sword of my mouth.
2 Cor 7:9 Now I rejoice, not that ye were made sorry, but that ye sorrowed to repentance: for ye were made sorry after a godly manner…. 2 Cor 7:10 For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death. 2 Cor 7:11 For behold this selfsame thing, that ye sorrowed after a godly sort,
2 Tim 3:1 This know also, that in the last days perilous times shall come.
2 Tim 3:2 For men shall be lovers of their own selves, covetous, boasters, proud, blasphemers, disobedient to parents, unthankful, unholy,
2 Tim 3:3 Without natural affection, trucebreakers, false accusers, incontinent, fierce, despisers of those that are good,
2 Tim 3:4 Traitors, heady, highminded, lovers of pleasures more than lovers of God;
2 Tim 3:5 Having a form of godliness, but denying the power thereof: from such turn away.
2 Tim 3:6 For of this sort are they which creep into houses, and lead captive silly women laden with sins, led away with divers lusts,
2 Tim 3:7 Ever learning, and never able to come to the knowledge of the truth.
2 Tim 3:8 Now as Jannes and Jambres withstood Moses, so do these also resist the truth: men of corrupt minds, reprobate concerning the faith.
2 Tim 3:9 But they shall proceed no further: for their folly shall be manifest unto all men, as theirs also was.
Revelation 2:14-16 Nevertheless, I have a few things against you: You have people there who hold to the teaching of Balaam, who taught Balak to entice the Israelites to sin by eating food sacrificed to idols and by committing sexual immorality.  Likewise you also have those who hold to the teaching of the Nicolaitans.  Repent therefore! Otherwise, I will soon come to you and will fight against them with the sword of my mouth.
•• Repent of anything associated with demons (in this Scripture = “eating food sacrificed to idols”) —
• Horoscopes, Ouija boards, witchcraft, New Age…
•• Repent of sexual immorality.
• A young adult Christian lady recently told me that she was shocked and distressed by the sexual liberties that many Christians take!
•• Repent of the doctrine of the Nicolaitans:
(1) A doctrine of exaggerated Christian liberty.
• I am personally amazed at the number of Christian pastors who regularly drink alcohol and see no problem with it.
(2) A tendency to “conquer the laity” — churches where the “clergy” dominate “the laity” need to repent. There is no such dictatorial rule in the bible.
Revelation 2:20-22 Nevertheless, I have this against you: You tolerate that woman Jezebel, who calls herself a prophetess. By her teaching she misleads my servants into sexual immorality and the eating of food sacrificed to idols.  I have given her time to repent of her immorality, but she is unwilling.  So I will cast her on a bed of suffering, and I will make those who commit adultery with her suffer intensely, unless they repent of her ways
Revelation 3:1-3 To the angel of the church in Sardis write: These are the words of him who holds the seven spirits of God and the seven stars. I know your deeds; you have a reputation of being alive, but you are dead.  Wake up! Strengthen what remains and is about to die, for I have not found your deeds complete in the sight of my God.  Remember, therefore, what you have received and heard; obey it, and repent. But if you do not wake up, I will come like a thief, and you will not know at what time I will come to you.
•• Repent of living on your past spiritual reputation.
• 2 Corinthians 6:2 “…now is the day of salvation.” We need to be growing in our salvation daily. There is no place in this life where we can be content to say, “I have arrived; I’m mature enough.”
•• Repent of falling asleep. Wake up!
• The devil is like the old “Sandman” many of us heard about in childhood — inducing us to sleep, sleep, sleep. The last thing in the world that Satan wants is a wide-awake, vigilant, on-fire Church!
•• Repent of receiving and hearing, but not obeying.
• James 1:22 Do not merely listen to the word, and so deceive yourselves. Do what it says.
Revelation 3:15-17, 19 I know your deeds, that you are neither cold nor hot. I wish you were either one or the other!  So, because you are lukewarm — neither hot nor cold — I am about to spit you out of my mouth.  You say, ‘I am rich; I have acquired wealth and do not need a thing.’ But you do not realize that you are wretched, pitiful, poor, blind and naked….  Those whom I love I rebuke and discipline. So be earnest, and repent.
•• Repent of growing lukewarm. This is perhaps the most dangerous mindset for a Christian. Jesus said He would even prefer us “cold” to “lukewarm” (vss. 15-16)! Clearly His greatest desire is that we be “hot” in our faith, on fire for Him.
•• Repent of self-satisfaction — “I am rich … I do not need a thing” (vs. 17).