The Kingdom of God naturally requires a change of heart, a change of life, which is why the Lord Jesus invited all to the Kingdom by saying, "Repent: for the kingdom of heaven is at hand." [Matthew 4:17[. For how can we dwell with a holy God, if we are not holy? [1 Peter 1:15-16]. It is through the Kingdom that we become sanctified, for the Kingdom pulls us up out of our present condition by giving us a greater calling, a higher responsibility.
Paul counseled the saints throughout his letters that after they had entered into the Kingdom through baptism of the water and the Spirit, they were to take off the old man of sin and walk in a newness of life. "What shall we say then? Shall we continue in sin, that grace may abound? God forbid. How shall we, that are dead to sin, live any longer therein? Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life." [Romans 6:1-4].
We are made free from sin through faith in the Lord Jesus Christ, but we must stand fast in that liberty and not entangle ourselves again with the yoke of bondage and sin [Galatians 5:1]. It is important to understand that a change in heart is not for a single moment in time and then you are done, but it is a continual process in which we crucify the old body of sin with the affections and lusts so that we might both live and walk in the Spirit. "Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new." [2 Corinthians 5:17].
Scriptures to Consider
1 Corinthians 6:9-11 (KJV)
9 Know ye not that the unrighteous shall not inherit the kingdom of God?... 11 And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
Romans 6:1-15 (KJV)
1:1 What shall we say then? Shall we continue in sin, that grace may abound? 1:2 God forbid. How shall we, that are dead to sin, live any longer therein? 1:3 Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? 1:4 Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life. 1:5 For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection: 1:6 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin. 1:7 For he that is dead is freed from sin. 1:8 Now if we be dead with Christ, we believe that we shall also live with him: 1:9 Knowing that Christ being raised from the dead dieth no more; death hath no more dominion over him. 1:10 For in that he died, he died unto sin once: but in that he liveth, he liveth unto God. 1:11 Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord. 1:12 Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof. 1:13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God. 1:14 For sin shall not have dominion over you: for ye are not under the law, but under grace. 1:15 What then? shall we sin, because we are not under the law, but under grace? God forbid.
Galatians 5:1, 16-25 (KJV)
1 Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage… 16 This I say then, Walk in the Spirit, and ye shall not fulfill the lust of the flesh. 17 For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would. 18 But if ye be led of the Spirit, ye are not under the law. 19 Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness, 20 Idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, 21 Envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God. 22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, 23 Meekness, temperance: against such there is no law. 24 And they that are Christ's have crucified the flesh with the affections and lusts. 25 If we live in the Spirit, let us also walk in the Spirit.
2 Corinthians 5:14-15, 17 (KJV)
5:14 For the love of Christ constraineth us; because we thus judge, that if one died for all, then were all dead: 5:15 And that He died for all, that they which live should not henceforth live unto themselves, but unto Him which died for them, and rose again… 5:17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.