The gospel is our Heavenly Father's plan of happiness. The central doctrine of the gospel is the Atonement of Jesus Christ. The Prophet Joseph Smith said, "The first principles and ordinances of the Gospel are: first, Faith in the Lord Jesus Christ; second, Repentance; third, Baptism by immersion for the remission of sins; fourth, Laying on of hands for the gift of the Holy Ghost" (Articles of Faith 1:4).
In its fulness, the gospel includes all the doctrines, principles, laws, ordinances, and covenants necessary for us to be exalted in the celestial kingdom. The Savior has promised that if we endure to the end, faithfully living the gospel, He will hold us guiltless before the Father at the Final Judgment (see 3 Nephi 27:16).
The fulness of the gospel has been preached in all ages when God's children have been prepared to receive it. In the latter days, or the dispensation of the fulness of times, the gospel has been restored through the Prophet Joseph Smith.