Jesus, as He taught and preached salvation, called to repentance those who would be saved. Repentance can be defined as a change of mind, a change of thought, and a change of one's behavior. It is a 180 degree about-face, a complete change of direction in the way we live life.
[Scriptures in Amplified Version]
Mat 4:17 From that time Jesus began to preach, crying out, Repent (change your mind for the better, heartily amend your ways, with abhorrence of your past sins), for the kingdom of heaven is at hand.
Mat 18:3 And said, Truly I say to you, unless you repent (change, turn about) and become like little children [trusting, lowly, loving, forgiving], you can never enter the kingdom of heaven [at all].
Mar 1:15 And saying, The [appointed period of] time is fulfilled (completed), and the kingdom of God is at hand; repent (have a change of mind which issues in regret for past sins and in change of conduct for the better) and believe (trust in, rely on, and adhere to) the good news (the Gospel).
Mat 3:1-2 (1) IN THOSE days there appeared John the Baptist, preaching in the Wilderness (Desert) of Judea (2) And saying, Repent (think differently; change your mind, regretting your sins and changing your conduct), for the kingdom of heaven is at hand.
Act 14:15 Men, why are you doing this? We also are [only] human beings, of nature like your own, and we bring you the good news (Gospel) that you should turn away from these foolish and vain things to the living God, Who made the heaven and the earth and the sea and everything that they contain. [Exod. 20:11; Ps. 146:6.]
Col 3:1 IF THEN you have been raised with Christ [to a new life, thus sharing His resurrection from the dead], aim at and seek the [rich, eternal treasures] that are above, where Christ is, seated at the right hand of God. [Ps. 110:1.] Col 3:2 And set your minds and keep them set on what is above (the higher things), not on the things that are on the earth.
Eze 18:30-32 (30) Therefore I will judge you, O house of Israel, every one according to his ways, says the Lord God. Repent and turn from all your transgressions, lest iniquity be your ruin and so shall they not be a stumbling block to you. [Matt. 3:2; Rev. 2:5.] (31) Cast away from you all your transgressions by which you have transgressed against Me, and make you a new mind and heart and a new spirit. For why will you die, O house of Israel? [Eph. 4:22, 23.] (32) For I have no pleasure in the death of him who dies, says the Lord God. Therefore turn (be converted) and live!
Rev 3:19-22 (19) Those whom I [dearly and tenderly] love, I tell their faults and convict and convince and reprove and chasten [I discipline and instruct them]. So be enthusiastic and in earnest and burning with zeal and repent [changing your mind and attitude]. [Prov. 3:12.] (20) Behold, I stand at the door and knock; if anyone hears and listens to and heeds My voice and opens the door, I will come in to him and will eat with him, and he [will eat] with Me. (21) He who overcomes (is victorious), I will grant him to sit beside Me on My throne, as I Myself overcame (was victorious) and sat down beside My Father on His throne. (22) He who is able to hear, let him listen to and heed what the [Holy] Spirit says to the assemblies (churches).
Act 17:24-31 (24) The God Who produced and formed the world and all things in it, being Lord of heaven and earth, does not dwell in handmade shrines. (25) Neither is He served by human hands, as though He lacked anything, for it is He Himself Whogives life and breath and all things to all [people]. [Isa. 42:5.] (26) And He made from one [common origin, one source, one blood] all nations of men to settle on the face of the earth, having definitely determined [their] allotted periods of time and the fixed boundaries of their habitation (their settlements, lands, and abodes), (27) So that they should seek God, in the hope that they might feel after Him and find Him, although He is not far from each one of us. (28) For in Him we live and move and have our being; as even some of your [own] poets have said, For we are also His offspring. (29) Since then we are God's offspring, we ought not to suppose that Deity (the Godhead) is like gold or silver or stone, [of the nature of] a representation by human art and imagination, or anything constructed or invented. (30) Such [former] ages of ignorance God, it is true, ignored and allowed to pass unnoticed; but now He charges all people everywhere to repent (to change their minds for the better and heartily to amend their ways, with abhorrence of their past sins), (31) Because He has fixed a day when He will judge the world righteously (justly) by a Man Whom He has destined and appointed for that task, and He has made this credible and given conviction and assurance and evidence to everyone by raising Him from the dead. [Ps. 9:8; 96:13; 98:9.]
2Co 5:17 Therefore if any person is [ingrafted] in Christ (the Messiah) he is a new creation (a new creature altogether); the old [previous moral and spiritual condition] has passed away. Behold, the fresh and new has come!
Rom 6:14-16 (14) For sin shall not [any longer] exert dominion over you, since now you are not under Law [as slaves], but under grace [as subjects of God's favor and mercy]. (15) What then [are we to conclude]? Shall we sin because we live not under Law but under God's favor and mercy? Certainly not! (16) Do you not know that if you continually surrender yourselves to anyone to do his will, you are the slaves of him whom you obey, whether that be to sin, which leads to death, or to obedience which leads to righteousness (right doing and right standing with God)?
Isa 45:22 Look to Me and be saved, all the ends of the earth! For I am God, and there is no other.