Respectfully, this is not how one approaches Christianity. Becoming a Christian means acknowledging God's authority over every aspect your existence, and submitting. If a new Christian were to read in the Bible says that he has to eat dog food for the rest of his life, then regardless of his dislike for dog food, guess what he needs to start doing? (Thankfully it doesn't say that.) But as a Christian you need to leave all pre-conceived ideas about anything and everything at the door, and start basing your life on what the Bible says.
But then again... If you could follow all the rules in the Bible you could as well be Jewish. Accepting God's authority and submitting to him is already what being Jewish is all about.
I'd say Christianity is about understanding God is the authority and a lot of his rules and his will is something you can't follow or aren't willing to follow - and there is the conflict. If God is the ultimate authority, you will be held accountable for that. Now, this doesn't mean you shouldn't strive to be what God wants you to be. It just means none of us is able to be that and that's why we need a Saviour to save us from this certain metaphysical destruction. And what's even better, this Saviour - when you put your trust in him - will give you more strength and will to be that better person. But again, you will never be completely free from the will to sin in this life. If you would, then the works of that Saviour would not be needed.
If Christianity would be about being a 100% good person who follows every rule in the Bible and never sins, then Christianity would be Judaism + having to believe in one another thing. It would be as hard as Judaism for us to follow plus one added thing to put on top of all that. It would not be a relief of any sort to anyone.
Of course this is not an excuse to continue sinning. You will naturally have a new perspective on sin and you will naturally have less will to sin and you will naturally sin less when you believe in Christ. If one hasn't changed their ways or thinking at all, the odds are one either doesn't really believe in it or one is dangerously close to stop believing, or maybe one is still taking extremely small baby steps towards the faith.
While it is true that we should be able to say sin is sin - and it would be dangerous to go and change the definition of sin and suddenly stop calling sinful things sinful things and at worst to start call sinful things as good things - we should always remember that while someone lives in sin and Jesus died for them too, Jesus died for
us too because we are not any different from those who we look at and see the sin in them. If we can't love the sinner, we can't love ourselves. If the sinner won't deserve our love, we don't deserve any love from anyone either.
I would say, though, what you said in that quote is very much true in the sense that Christ's words and what is said in the Bible in the context of Christ is absolutely the ideal we should aim towards and we should give effort to meet that target. But that isn't what makes or breaks it.
(and I have to say what you wrote earlier in that longer post was very well written! So I'm not trying to correct you on any of that here - and I'm not trying to correct you with that quoted text either - I just mean this as digging down a bit deeper with what you wrote in that quote because the way it now is, and while it's basically a simple thing to understand and while it's important to also say how tight and firm one should be in their walk with Christ, I think it's also very important to look a bit into why we can't be perfect so that those who struggle won't lose all their hope)