Ezra Taft Benson said:
A most priceless blessing available to every member of the Church is a testimony of the divinity of Jesus Christ and His church. A testimony is one of the few possessions we may take with us when we leave this life.
To have a testimony of Jesus is to possess knowledge through the Holy Ghost of the divine mission of Jesus Christ.
A testimony of Jesus is to know the divine nature of our Lord’s birth—that He is indeed the Only Begotten Son in the flesh.
A testimony of Jesus is to know that He was the promised Messiah and that while He sojourned among men He accomplished many mighty miracles.
A testimony of Jesus is to know that the laws which He prescribed as His doctrine are true and then to abide by these laws and ordinances.
To possess a testimony of Jesus is to know that He voluntarily took upon Himself the sins of all mankind in the Garden of Gethsemane, which caused Him to suffer in both body and spirit and to bleed from every pore. All this He did so that we would not have to suffer if we would repent. (See D&C 19:16, 18.)
To possess a testimony of Jesus is to know that He came forth triumphantly from the grave with a physical, resurrected body. And because He lives, so shall all mankind.
To possess a testimony of Jesus is to know that God the Father and Jesus Christ did indeed appear to the Prophet Joseph Smith to establish a new dispensation of His gospel so that salvation may be preached to all nations before He comes.
To possess a testimony of Jesus is to know that the Church which He established in the meridian of time and restored in modern times is, as the Lord has declared, “the only true and living church upon the face of the whole earth.” (D&C 1:30.)
To possess a testimony of Jesus is to receive the words of His servants, the prophets, for as He has said, “whether by mine own voice or by the voice of my servants, it is the same.” (D&C 1:38.)
A testimony of Jesus means that you accept the divine mission of Jesus Christ, embrace His gospel, and do His works; it means you accept the prophetic mission of Joseph Smith and his successors.
Speaking of those who will eventually receive the blessings of the celestial kingdom, the Lord said to Joseph Smith: “They are they who received the testimony of Jesus, and believed on his name and were baptized after the manner of his burial, being buried in the water in his name, and this according to the commandment which he has given.” (D&C 76:51.) These are they who are valiant in their testimony of Jesus, who, as the Lord has declared “overcome by faith, and are sealed by the Holy Spirit of promise, which the Father sheds forth upon all those who are just and true.” (D&C 76:53.)
“Those who are just and true”! What an apt expression for one valiant in the testimony of Jesus. They are courageous in defending truth and righteousness. These are members of the Church who magnify their callings in the Church (see D&C 84:33), pay their tithes and offerings, live morally clean lives, sustain their Church leaders by word and action, keep the Sabbath as a holy day, and obey all the commandments of God.
Ezra Taft Benson, “Valiant in the Testimony of Jesus,” Ensign, May 1982, 62