There are many kinds of law, it is a very complicated subject. God's law cannot stand along, all scripture is truth and each must be learned and acknowledged. Even the world, whose ways are so opposed to God's ways, have law. We don't run a red light in the world.
The law alone, without Christ, cannot save, but if your faith in Christ is only that He is able to forgive sins, it isn't actually faith in Christ, only faith in his ability to forgive our sins. I we do not repent of them, but prefer to keep them, Christ lets us do that.