All those who come to Christ Jesus, believing on Him as The Only Begotten Son of God, that He only died on the cross to redeem us from our sins, is a ‘requirement’ to being saved (John 1; 3:15-21; 3:36; 5:24; 6:40; 7:37-39; 20:30; Acts 10:43; 13:19; 16:30-31).

Rom 10:8     But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;
9    That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised Him from the dead, thou shalt be saved.
10    For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
11    For the scripture saith, ‘Whosoever believeth on him shall not be ashamed.’ [Note: Paul quoting from Isaiah 49:23 and 28:16]

Rom 10:12     For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon Him.
13    For whosoever shall call upon the name of the Lord shall be saved.

     After our ‘confession’ of believing on Christ Jesus, He also commanded His to do certain acts to ‘seal’ us with His Covenant, such as repenting and being baptized in His Name, and observing Holy Communion, and continuing in His Word (Mark 1:15; 16:16; Acts 2:38; Acts 8; 10:47-48; Acts 18:8; Acts 22:14:16; Matt. 26:26-29; Mark 14:22-25; 1 Cor.10 & 11; Isaiah 8:16; John 8:31).
     But believing, repenting, and being baptized in His Name is only the first step to truly be ‘in Christ’. (Not to go into depth here, but it’s important to know our LORD also has Power to save without ‘water’ Baptism, such as the case with the malefactor crucified with our Lord who believed; Luke 23. That was a special example to show us God’s Power. Those who can get baptized, have no excuse, especially in the Western Christian Nations where we worship God through His Son in liberty and in freedom still).
     The ‘major’ purpose of this flesh age existence is for God to bring That Salvation through Christ Jesus, His Son, to us, redeeming all those who ‘believe’, back to Him by defeating the devil (Heb.2). That Promise of Salvation was first given through Abraham (Gen.12 & 17). And The Word ‘hinted’ at It all the way back in Genesis 3:15.
     Concerning sin, all one has to do, is look around today. Can we honestly say that any of us actually know someone totally ‘without sin’ today? We all ‘sin’ in this flesh (again see Romans 7 and Gal.5 as to what Paul taught about the war between flesh and the Spirit). Christ Jesus is The Only One ‘totally’ without ‘any’ sin, Who came to earth, born of woman just like us, but was slain and then in Glory resurrected to the Right Hand of God. If Christ had sinned, He wouldn’t be the Perfect Sacrificial Lamb of God for us. We would be left of our own flesh infirmities and failures, lost, with no hope, left with the world’s devices. And this is why ‘we all’ are, and must be, born into sin in this flesh once (Gal.3:22; Heb.9:27); it’s God’s Way to show us that we need Him, and Him only for Salvation! (see Isaiah 44:6-8; Deut. 4:35; 4:39; Deut. 32:39-43, as “His people” and “nations” there mean ‘all’ who accept Christ Jesus; also see Isaiah 45 especially).

Titus 3:3-8
3    For we ourselves also were sometimes foolish, disobedient, deceived, serving divers lusts and pleasures, living in malice and envy, hateful, and hating one another.
4    But after that the kindness and love of God our Saviour toward man appeared,
5    Not by works of righteousness which we have done, but according to His mercy He saved us, by the washing of regeneration, and renewing of the Holy Ghost;
6    Which He shed on us abundantly through Jesus Christ our Saviour; 7    That being justified by His grace, we should be made heirs according to the hope of eternal life.
8    This is a faithful saying, and these things I will that thou affirm constantly, that they which have believed in God might be careful to maintain good works. These things are good and profitable unto men.
(KJV)

     Notice the last verse here of Titus 3:8 about being “careful to maintain good works.” Like was said a previous time, and as written in Rev.14:13, our ‘works’ follow us to Heaven. And that means our ‘good’ works. So what happens to our sins after we repent to Christ Jesus? That’s what that word ‘remission’ means; literally wiped away, forgotten (1 John 1; Heb.10).
     To be ‘perfect’ in The Lord is to ‘want’ to follow Him, to ‘want’ to do right, even though we may fall short, and we will while we are still in this flesh body, for the ‘flesh’ cannot please God. It’s the acts of allowing His Spirit to work through us, doing work for Him, which justifies our spirit in Him (Romans 8). The ‘flesh’ is not of our Father’s original first Plan for us before Lucifer rebelled. God brought the flesh state because of Lucifer’s rebellion against Him, and the drawing away of one third of God’s children (Rev.12). But while we are still here in this ‘flesh’, those who claim The Salvation Promise have got work to do, fulfilling a Mission for our Lord. Let’s not be slack in it, for it’s an honor and a ‘pleasure’ to serve Him. His Letter He gave us, The Word of God, instructs us on ‘how’ to serve Him according to His Will, not ours. That’s where many believers on Christ fail, listening and following those who use man’s human nature to form morals, and thus leaving the Doctrines of Christ. God’s Word has the only true set of morals for us to follow. And in this dispensation time of ‘Grace’, He gives us His Holy Spirit to guide us in that. The Word solidifies our understanding of true righteousness, as aided by His Spirit.
     So… that’s a ‘general’, and ‘specific’ coverage of what we ‘must do’ to be saved, and go to Heaven. Is there anything written about those who sin ‘against’ Christ; those who will not get into Heaven? Romans 1 and Galatians 5 both cover some of those, with the ‘works of the flesh’:

Gal 5:16-21
16    This I say then, Walk in the Spirit, and ye shall not fulfil 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.
(KJV)

But the ‘works’ of the Spirit are:

Gal 5:22-26
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.
26    Let us not be desirous of vain glory, provoking one another, envying one another.
(KJV)

     Simply, if we always do works which are the ‘fruit of the Spirit’, then we are not under The Law, for those good works are not ‘against’ God’s Law. That is our ‘liberty’ in Christ today. To go against the Spirit, means to give up that liberty in Christ, and walk after the flesh. The Law then certainly applies in that state. That’s still easily seen today with one going out getting into trouble for stealing, etc. How does God’s Law apply to those? When caught, they’ll most likely go to jail, as many our civil laws were originally based on God’s Law directly from His Word. And the framers of our U.S. Constitution also knew this; that’s why they wrote about some of these matters in their writings. They understood God’s Plan.

The word ‘convert‘ is in the KJV in Isaiah 6:10, and it’s about those who ‘convert’ back to God with their hearts, and their minds, knowing His Truth, doing His Will. The phrase which even our Lord mentioned in Matt.13, about ‘eyes to see and ears to hear’ is mentioned there in Isaiah 6 also. That Hebrew word ‘shuwb‘ translated ‘convert‘, means ‘to turn back; to return’ (Strong’s no. 7725). Salvation through Christ Jesus means ‘returning’ back to God, as His People. Even the New Name God gave to Jacob, that of ‘Israel‘, has a special meaning for ‘all’ those who receive God’s Grace of Salvation through Jesus Christ. That word ‘Israel‘ means “God prevails” (Strong’s no.3478 from two Hebrew roots of ‘sarah‘ meaning ‘to prevail’, and the other ‘El‘, i.e. ‘The Almighty’). In Gen.32:28 God gave that Name to Jacob because he ‘prevailed’ with God’s helping hand. The New Testament uses the word ‘overcome‘ in the KJV in the same sense as to ‘prevail with God’ (Rev.2:7; 1 John 4:4; 1 John 2:13-14; Romans 12:21).
     Thus, to be an ‘overcomer’ in Christ, is to be working ‘with’ God, overcoming this world of evil. Each must ‘overcome’ to go to Heaven, to be part of God’s Israel. And Christ makes our ‘yoke’ light, helping us every step of the way. For as written, “If God be for us, who can be against us?” (Rom.8:31).

TO SUMMARIZE: Confession that Jesus of Nazareth is God, ‘Emmanuel’ in the flesh (Matt.1:23), our Savior, and that only through Him do we have Salvation, is the first step in going to Heaven. Then repentance to Him, and baptism in His Name, following what He told us to do as best we can, are the next required steps. Our repentance to Him is no different than a child who messes up, and goes to their flesh father, asking for forgiveness. That flesh father will naturally wish to embrace their child in love, and actually forgiving them, bringing the child back into ‘the fold’. So we shouldn’t beat ourselves up with ‘guilt’ trips once we’ve repented to our Lord, asking forgiveness, and trying not to do the sin again. Our Lord doesn’t want to hear about it anymore after repentance.
     Thus, one who refuses to repent, not accepting Christ, who ‘loves’ to sin, and even show others how to sin, will not go to Heaven. That is the ‘habitual sinner’, one who actually does not care if they sin or not. They will not have a place among God’s elect in Christ’s future Kingdom (Romans 1; Galatians 5; 2 Peter 3, Matt.25; Luke 16 with Lazarus and the rich man; and many other Scriptures in Isaiah Chapters 1 throughout.)
     Further, if you understood about Christ’s Millennium reign of a thousand years with His elect, many who fall and stumble today, who really don’t have a ‘chance’ at coming to Christ, will have ‘their’ chance during that thousand years. And that can never apply to one who is ‘called’ today, meaning one who ‘hears’ by God’s Grace today. Many in the world don’t have a ‘clue’ as to what God’s Plan is about, and are not ‘in Christ’. But we, being ‘in Christ’, who are ‘called’ during this dispensation time of ‘Grace’, cannot afford to be slack on ourselves, otherwise we crucify our Lord all over again. And I mean this in the sense of one who comes to Christ, and then later flat refuses Him in their life, and turning to the world, because of not keeping the ‘faith’. Repentance to Christ when we sin, trying to do His Will, and staying on Christ, is keeping the ‘faith’. Paul taught about this in Hebrews 6. And the Book of James also covers much of our needed attitude to stay ‘in Christ’. The Word teaches against a “once saved, always saved” type of thinking. Those with free-will, not specifically being ‘chosen’ for a special Mission in Christ, can fall away from Him. 2 Thess. 2 with “fall away” is the Greek word ‘apostasia‘, meaning ‘apostasy’ away from Christ. Only one who once ‘believed’, can become apostate away from Christ. It doesn’t apply to one who hasn’t accepted Christ yet.