Because there is a refusal to see the cross as something that cuts us off completely from what causes us to sin. Rather, people are satisfied to continue to try to improve themselves without going to God for the full measure of grace.
That you describe others in these words does not make it so. I've been repeating to you this very message straight from the Bible but you have refused to receive it. That we are crucified in Christ, that we have died to sin, and to the flesh, and you claim it is not so, though the Bible teaches this explicitly. And in my life I find no disagreement with God's Word. In this truth is in fact power over sin and flesh.
We have been crucified together with Christ. This is the foundation of being born again. This is our death, that precedes our rebirth, and in rebirth, we are born bearing our Father's nature. In faith we walk in that new nature.
It is our responsibility (on us) to get God's attention and prove to Him our sincerity in laying down our lives in selfless abnegation.
This is your refusal. That having been born again, we then must go on to prove ourselves to Him, He Who knows us, having made us, having been with us, able to see in us places we cannot see, yet we are to "prove" something to Him, to convince Him, "ME, I am ready, I have prepared myself for you!" To somehow catch His eye with our sparkle, something in ourselves, some virtue in ME, some way I distinguish myself above all the rest, and only then will God give us actually all we need for life and godliness.
He is my Father, not far away, but here, with me, I don't have anything to prove to Him, He is the one who reveals me to myself. It's He Who is training me, in His wisdom.
The kingdom walk is not for the faint of heart. Hence so few are permitted access.
Galatians 5:24-25 KJV
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.
All who are Christ's are admonished to walk in the Spirit. Shall we believe that we are able to, as we trust in God's power? Does He tell us to do that which we cannot? I don't think so, and I don't find it so.
Romans 5:1-2 KJV
1) Therefore being justified by faith, we have peace with God through our Lord Jesus Christ:
2) By whom also we have access by faith into this grace wherein we stand, and rejoice in hope of the glory of God.
The same faith in Jesus by which we are justified - declared so by God, and not we ourselves - the same faith in Jesus by which we are justified is the same faith by which we have access into the grace in which we stand.
We are told in no uncertain words, that we are to stand. In His grace we stand, entered into by faith. Again, does He not give the power to do as He tells us to do? I believe He does, and I find it so in my life.
Ephesians 2:8-10 KJV
8) For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
9) Not of works, lest any man should boast.
10) For we are his workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them.
We are not men of our own making, making ourselves so very humble that God will notice how special we are, and will give us the key to the Real Christian Life.
We are men of His making, knowing that of ourselves, we are nothing, I am nothing, I don't make myself anything in His eyes, I receive His working in me or I have nothing at all.
2 Corinthians 3:18 KJV
But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord.
Seeing His glory shone in us changes us into His image. Open faced because we have no guilt, no shame, nothing to hide.
If you respond with how I'm just spouting religious indoctrination to support my flesh, that will be simply more of the same. Or you can take a higher road, it's up to you.
Much love!