Hyper-grace proposes when mixed with calvanism, OSAS, once you have faith at somepoint you are saved.
In this formula all sin is forgiven from Christ onwards for everyone, and sin is no longer an issue.
Another proposal is put forward by Paul. The law condemns and does not bring righteousness or acceptability before God.
It is the right relationship, the understanding the heart of the Lord and his intentions that matter. This is expressed in belief or faith in God.
This faith in Christ means we are not under the law anymore, but under the Spirit, born again, walking in fellowship with Christ. The outflow of our hearts is to follow and obey Christ, to do the things he asked of us. As a measure of the work done in us we follow. This following is perfection, acceptable to God as long as we exercise faith, which is counted as righteousness. If we continue in sin, faith in the end becomes lost to us, so we loose our righteous standing before Christ and God.
"Teacher, what good thing must I do to get eternal life?" Matt 19:16
"If you want to be perfect, go, sell your possessions and give to the poor, and you will have treasure in heaven. Then come, follow me." Matt 19:21
But I tell you, love your enemies and pray for those who persecute you, that you may be children of your Father in heaven. Matt 5:43
Be perfect, therefore, as your heavenly Father is perfect. Matt 5:48
But love your enemies, do good to them, and lend to them without expecting to get anything back. Luke 6:35
Be merciful, just as your Father is merciful. Luke 6:36
Matthew uses the term perfect twice. Once in terms of salvation, following Christ is to find eternal life, perfection.
Loving your enemies is being perfect. Luke softens the word by using the word merciful, which is more specific to the meaning of loving your enemies and closes off the idea we are perfect in everything.
So our standard in following Christ is achievable through fellowship with Christ. It is the faith we have that deems us righteous, not our behaviour, though our righteous behaviour is the fruit of the relationship. If we loose our relationship we loose our righteousness. This negates the idea of one sin invalidates fellowship or faith, but persistant sin does, because it breaks the relationship. If you have teenage children you will know the line between being an independent adult and respectful to your parents, often get mixed up with destructive results. Sometimes the break is permanent, sometimes it comes back.
The problem with calvanism is the assumption a break is impossible. Peter could have broken his relationship with Christ when he denied him, but it was his faith that remained strong and saved him. Judas did break this faith, and denied Christ was the messiah, just a lunatic preacher who could be sold to the highest bidder. He lost his faith.