You know the difference between visiting somewhere and living there, right? Christians aren't perfect, but they don't LIVE in sin. Or again, you know the difference between growing and not growing. My daughter is 13, and I cannot tell the difference between how old she is today compared to yesterday. But I can definitely see a difference since ten years ago. In the same way, we grow in Christ, we mature and sin less and less. But some people have been in the church for decades, and there's no difference. They deceive themselves. Whatever doesn't grow dies.
Don't feel like if Christ's blood covered, let's say a lie, that lies are now off the list and can't be forgiven if it happens again in the future. Is there a process of elimination when it comes to sin? If a husband is in the habit of not coming home for a few nights in a row, and that habit turns into weeks, then months, he is no longer living there. In that case it's a bad thing, but if it was good to leave, and it didn't happen immediately, but it was happening, then eventually that person is no longer living in that situation.
Christ didn't die for nothing, your sins are covered as long as you are in Christ. But those who use His blood as a license to sin, live in sin, and therefore become disqualified for the prize. Don't sin on purpose, run from sin, but at the same time, have faith in the power of Christ's blood. If you truly love Him you will sin less and less. I used to smoke, now I don't. It's been years since I smoked, but it took a long time to quit. A Christian will not continue to sin.