When we believe, we will be blessed with the Spirit. We will manifest in our words and actions that we know the truth and have a desire to do good—which is always a confirming sign of the working of the Spirit in our lives. Our duty is to accept and apply all of the saving doctrines revealed unto us. We are not to be selective—we apply them all. Elder Bruce R. McConkie emphasizes this point:
Belief in the various truths must be accepted if salvation is to be won, cannot be parceled out in such a way as to accept one essential truth and reject another. All phases of the doctrines of salvation are so intertwined with each other that it is not possible to believe one part without also believing all parts of which knowledge has been gained. Thus no one can believe in Christ without believing in his Father also. (Matt. 11:27; John 5:23; 6:44; 12:44–46; 14:1, 6.) And no one can accept Christ without accepting the prophets who testify of him. (Mormon Doctrine, 2d ed. [Salt Lake City: Bookcraft, 1966], 78)
When we act with faith to believe the things of God, we are richly blessed with the manifestations of the Spirit so that we know that these things are true. When we believe in the Lord, we will believe the words of His chosen servants and follow their counsel. Let us trust in the Spirit, for it will persuade and lead us to do good (see D&C 11:12). Remember that all good comes from God (see Alma 5:40; Moroni 7:12, 22). He persuades, leads, and inspires us to do good. When we live the doctrines, we will know that they are of God (see John 7:16–17). If we fail to believe the Lord’s words, we fail to believe in Him. Those who don’t believe in the Lord and fail to repent will be cast off (see 2 Nephi 30:2). Abinadi has proclaimed, “He is the light and the life of the world” (Mosiah 16:9). Let us look to our Savior (see Moroni 7:15–17) and respond to the influence of the Spirit, which will lead us to do good (see D&C 11:12). Let us remember that we are in a fallen state, as the brother of Jared confessed—“because of the fall our natures have become evil continually” (Ether 3:2)—and thus we need the help of our God in all things.