Jesus defined what he means by “the gospel.” It is, first and foremost, his coming to earth to do the will of his Father—which includes faith in his atonement, repentance, baptism, the gift of the Holy Ghost, and enduring to the end. For emphasis, he repeated and summarized: The gospel, or the good news or glad tidings, includes faith in the Lord Jesus Christ and his atonement, repentance, faithfulness to the end, baptism, receiving the Holy Ghost, and judgment. No one can enter into “his rest,” which is “the fulness of his glory” (D&C 84:24), unless he is cleansed by his atoning blood.
The doctrine of Christ is that we embrace the Atonement through the first principles and ordinances of the gospel. These are the works by which we shall be judged (3 Nephi 11:31–41).