People like to curse a lot. I grew up in a house filled with profanity, and even after nearly 40 years of being a Christian it is still an effort to choke off those words as they pop up out of my memory-banks.
God curses, too, but He never uses profanity. God curses certain types of human beings. What curse-words does God use? God's curse-words are the Ten Commandments.
Who are the human beings whom God curses? Anyone trying to gain everlasting life by keeping the Ten Commandments. "Cursed is everyone who does not continue in all things which are written in the book of the law, to do them" (Deuteronomy 27:26, quoted by Paul in Galatians 3:10).
If you are trying to attain everlasting life, or retain it, by keeping the Ten Commandments, God curses you. Why? Because God's standard is that you must continue in them -- not just do them occasionally, or even "a lot". You must do all of them -- not some of them; and that includes laws like circumcision and the food laws, too. If you fail to continually do all of them, God curses you.
Do you keep all the commandments, all the time, perfectly in motive and performance? No? Then you are cursed with eternal death. Even if you are a Christian. If you say that you must keep the commandments to be saved. This is what Paul in Galatians is saying to you.
But Paul goes on to say: "The fact that no one is justified by the law in God's sight is obvious" (Galatians 3:11). Notice Paul doesn't say that this fact is mysterious, or hard to understand. No, Paul says this doctrine is obvious ("evident" in the NKJV).
You have to be spiritually blind not to see it. Only an blind person would claim that God lowers the bar of His law down to where we can (sort of) jump over it, or that God gives us a 50% curve on our failure rate. If someone claims that God grades on a curve, they are ignorant of the Law, or in denial.
Paul quotes Habbakuk 2:4: The just shall live by faith. Habbakuk meant this in the original historical sense that the just Jew would survive the judgments God was about to pour out on Israel for her sins. But Paul applies that truth in a deeper, wider sense. God justifies the sinner by faith, and that is why the sinner inherits everlasting life.
"But maybe then we need to keep the law as an expression of our faith, and in that way we are partially justified by law!", someone might say. Paul says this: "The law is not of faith" (Galatians 3:12). In other words, there isn't any part of the Law that has a "faith character" to it.
You can begin reading law in Genesis 17, then start with law proper in Exodus 20 and read to the end; you can read the book of Leviticus from end to end; and you can read the entire book of Deuteronomy, and you know what you do not find? Faith.
The Law is 100% doing what God requires of you. It is No % trusting what Christ has done for you. Read Galatians 3:12.
But do you want to know what you will be accused of, if you preach this today? You will be accused of being a liberal. You will be accused of supporting "easy believism." You will be accused of encouraging sin, and you will be accused of fostering false, nominal conversions. A theological savvy person will accuse you of being "antinomian."
But if you have never been accused of promoting moral liberalism, of promoting "easy believer-ism", of encouraging sin, of fostering false conversions, or of antinomianism .... then, my friend, you haven't preached the Gospel yet.