We are not under law, but under grace. Hence, we should not be living the Christian life as one big struggle with law. Paul describes in Romans 7 the plight of every man who wants to obey God through law but finds himself hopelessly lost in that effort. There is now no condemnation for those who are in Christ Jesus. But this is a frustration for us. We are not saved by law nor under law, but if we practice what is lawless, we evidence that we are not saved. Doesn't this mean we're under law? Yet, we are told that we are not, but under grace instead. So which is it? Those who practice lawlessness are cast off from the presence of Christ on judgment day, but those who seek to be saved by obeying the law are hopelessly lost and without salvation.
Many people end up thinking the Bible is just a big contradiction on these points, but the problem is that this theology is all found within the same authors, not different authors with different ideas of salvation. In fact, many of these ideas are found in the same books, so it isn't just a matter of the authors changing their minds over time either.
So what's the deal? Are we under law or not? The answer is found in understanding that the Bible has always only required of us one commandment as opposed to juggling the many. The one commandment has always been laid out for us from the beginning: Love God as your primary love in life. That's it. All of the other laws simply exist to direct that love into what God desires versus what He does not. Love wishes to do what its beloved desires, so those laws simply tell us where to go with our love for God.
This brings us back to being saved by grace. We are not saved by grace. We are saved by grace through faith, and that faith is toward God through Jesus Christ. Faith in the Bible has to do with allegiance, unification, and love. It's not just something you believe in your head. Hence, we are saved through a relationship with God where our pursuit is of God as our primary love. The reason why many are cast out from His presence on judgment day for being lawless, then, is not because they were supposed to be under law, but because they did not love God so as to seek those things that are pleasing to Him. They evidenced a hatred toward God by shunning what God had revealed as pleasing to Him in the principles of the law. Hence, they are lawless and were never known by Christ (i.e., never had a relationship with Him where He was the primary love of their lives).
On the flip side, there are those who are continually struggling with the law, because they have come to believe that the Christian life is a life filled with many laws. They become overwhelmed. They are drowning in a law that continually screams to them that they are not even close to being perfect. This brings depression and disillusionment, as the Christian life was never about the attempt to fulfill the law as a means to be acceptable to God. It is about loving God through Christ, being restored to God through His death, and being continually reconciled to Him through His resurrection and intercession for us. In other words, it is about a love relationship with God. The individual laws only help us understand what God desires, and so we pursue that because we are saved, not in order to be saved. We direct love upon those pathways because God has revealed what is pleasing to Him, i.e., what is good; and so we pursue Him through those things. We do not pursue those things for ourselves. We do not do them to become better people. We do not do them because they give us a better life now. We do not do them to be acceptable to God in the hope that He will save us in the end. We have no hope of that through laws, but our salvation is in our relationship with Him, and He has provided for us the means to have that relationship through Christ and His work on the cross, in His resurrection, and in His heavenly intercession on our behalf.
Now, of course, no one is perfect in their love for God either. That's not that point. The point is that a relationship with God should be characterized by the refraining from evil, the doing of good, and repentance when we fail to love God as we should; but it should not be characterized by a juggling of laws that sit over us as something to fulfill ourselves so that we might be righteous before God. If you think it is, good luck with that.
Without God as our primary love, and without seeing those laws as merely examples of principles of the good that pleases God, those laws become cold, dark reminders of our distance from God and condemnation. O Wretched Men that we are. Who will save us from this body of death? But thanks be to God through Jesus Christ that we are in Him, and therefore, no longer condemned by those laws. Hence, we can now see them as guides to direct our love for God rather than as instruments of our destruction.
As you can see, this isn't a juggling of the law. We are not under law. We are not saved by law, but instead by the rule of Christ, the rule of faith, the law of love, a relationship with God through Christ that seeks Him first over all.
So there was ever only one commandment we were, are, and are to obey, and that is to love the Lord your God with all your heart, all your mind, all your strength, and everything you've got. Those who pursue this have no need to juggle the law in order to be saved. They are given salvation freely by the One with whom they have entered that loving relationship. There is now no condemnation for them, because the law isn't a vehicle of salvation for them. It is merely a code of examples that direct our expressions of love toward God, as we fill up our relationship with Him with more and more love. And this is the love of God, that we obey His commandments. We express our love for Him through refraining from that which the law helps us see as evil, and doing that which the law helps us see as good, and repenting and seeking God over all things whenever we have failed to love Him through those expressions.
So there is no contradiction in saying that we are not under law, but under grace, and those who practice lawlessness will not inherit the kingdom of God, because we are saved by a faith that loves God and seeks to express that in submission to what the law reveals as good, and only those who do not love God seek otherwise.
The one commandment, then, is a commandment to come into a relationship with God through Christ where you pursue Him as the most loved One in your life. There is no need to burden yourself with the law as a whip behind you, as there is no judgment for you, only the love and salvation in a relationship with God that the law directs toward the right expression.
So there is only the one commandment. And either you seek to obey it or you don't.