Mosiah 13

28 And moreover, I say unto you, that salvation doth not come by the law alone; and were it not for the atonement, which God himself shall make for the sins and iniquities of his people, that they must unavoidably perish, notwithstanding the law of Moses.

Abinadi said that it is expedient that the people keep the law. Jesus said, "If ye love me, keep my commandments." (John 14:15) But salvation cannot be earned by obedience to law. Our own works are essential, but never sufficient, for salvation in the kingdom of God. We need the redemption possible through Christ's intercession for us. We become eligible for the blessings of the atonement as we love Him and keep His commandments, but it is His supreme gift and sacrifice alone that makes our salvation and eventual exaltation possible.