Those who teach a repent of your sins/submit to Jesus as Lord of your life for Salvation live in utter denial of how sinful they are. They become convinced that because they've stopped swearing, stopped drinking, started going to Church, started reading their Bible, and started praying that they have made Jesus the Lord and Master of their lives.
Because such ones honestly believe that they are good people, they hate the idea that someone could still "live in sin" and get to Heaven. The implication is, of course, that they don't "live in sin", or at least not "willful, habitual sin". Yes, they do. You, right now reading this, live in willful, habitual sin. All sin is willful in the sense that you choose to do it, since you are never tempted above that which you are able to resist (1 Corinthians 10:13).
Jesus Christ kept the law of God perfectly, and He's the standard. If you are coming short in any way - to any extent - of Jesus Christ, that is sin. Disobeying anything that God told you to do is a sin (1 John 3:4), as you are breaking His commandments, of which there are hundreds in the Bible.
Take a note as to how high the standard is:
You live in willful, habitual sin. The only people who claim not to don't know how high the standard is. The standard is Jesus Christ (Acts 17:31, Romans 2:16). Neither you nor anyone else has made Him "Lord of All" in your life.
That's why it's so pathetic when these false prophets get up and put on a grand show as to how you have to submit to the Lordship of Jesus Christ and repent of your sins to be saved. They haven't repented of their sin. It's not possible to live up to that standard. They are unknowingly binding burdens to people which they themselves can't bear, just like the pharisees (Matthew 23:4).
If the Bible is true, you don't do good (Ecclesiastes 7:20, Psalm 14:2-3), you are not a good person (Romans 3:12, Matthew 19:17, Mark 10:18, Luke 18:19), you sin (Romans 3:23), you live in sin (1 John 1:8, 10), you are unrighteous (Romans 3:10-12) even when you try to be righteous (Isaiah 64:6).
If someone thinks that they are going to go to Heaven because they've made Jesus the Lord and Master of their lives, they are deceived. They have constructed a lenient, imperfect standard of Lordship in their minds in order to think that they meet it.
In these people's mind, as long as you aren't doing the "big sins" like adultery, drugs, stealing, murder, etc., then you've repented of your sins, and made Jesus "Lord of all". Not even close.
These people don't understand what would be involved if total Lordship was actually required. You wouldn't have a house. You wouldn't have a car. You wouldn't have a wardrobe, or a secular job, or free time, or a phone, or any of the luxuries that every last one of these fake Lordshippers have, because you would have sold all that stuff and given it to the poor or the church, and would be spending 100% of your time either in prayer, or preaching to and helping others. No one does that, or even comes close.
When these people who live pretty average lives in terms of their behavior say "I think you will live a changed life if you're really saved", they show what they are trusting to get them to Heaven. They are subtly boasting about how good they are (in contradiction to Ephesians 2:9), even though they are barely above average at best, and certainly far below what God expects, even at their best state (Psalm 39:5).
In summary, every Lordship Salvationist lives far short of God's standard, and none of them has made Jesus "Lord of all".
Such a thing would require sinless perfection, even if the holders of this false doctrine pretend it wouldn't, because they redefine "all".