2 Nephi 25:27

Wherefore, we speak concerning the law, that our children may know the deadness of the law; and they, by knowing the deadnes of the law, may look forward unto that life which is in Christ, and know for what end the law was given. And after that, the law is fulfilled in Christ, that they need not harden their hearts against him, when the law had ought to be done away.

So we talk about the law. We want our children to know that the law is dead. When they know the law is dead, they can look ahead to the life that is in Christ. They will know why the law was given. After the law is finished in Christ, they won’t need to make their hearts hard against him. This is when the law should be done away with.

We teach about the law so our children understand it’s dead now. Once they know the law is dead, they can look to the life that’s in Christ and understand why the law was given in the first place. After the law is fulfilled in Christ, they won’t harden their hearts against him when the law should be set aside.