For sure, there are things that we mourn but one of the many things Christ came to do was to give us a clear conscience from sin.
We have a clear conscience because Christ freed us from the law and all things are lawful for us. Those who accept that liberty usually don’t sin much any way because they have the fruits of the spirit, a new nature. But if they slip up, they ask for forgiveness and move on, they don’t dwell on it.
I'm feeling a bit overwhelmed with this subject still. But maybe if we tackle it a bit a time.
We need to look at the whole counsel of God, taking all the scriptures in balance with one another, rather than isolating one verse.
Where it says All things are lawful, but not all things are expedient/helpful. We have to balance that with where it is also warning in that very same 1 Cor 6 passage of scripture, part of the context of that verse, that people who are living in sin will not inherit the kingdom of God. If we come to faith in Christ and keep living or go back to living in sin as we were before knowing the Lord we will disqualify ourselves. Pig returning to the mire, dog returning to its vomit.
1Co 6:9-10
Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals,[fn] nor sodomites,
nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God.
And the bible says this:
Heb 10:26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, ( I understand the grammatical tense there as being "if we keep on wilfully sinning...")
Says elsewhere that God is not mocked.....there are so many warnings in scripture not to abuse God's grace essentially. A three-fold cord is not easily broken, but it certainly can be. We will prove or disprove our faith by how we live.