Sometimes, we may believe that Old Testament prophets somehow didn’t understand Grace and its inclusion in the Atonement. Of course, almost all of the great Book of Mormon prophets taught and testified during Old Testament times and they taught powerfully of the Atonement.
A search of the Old Testament reveals that prophets in Israel comprehended the concept of Grace very well.
9 Behold, O God our shield, and look upon the face of thine anointed.
10 For a day in thy courts is better than a thousand. I had rather be a doorkeeper in the house of my God, than to dwell in the tents of wickedness.
11 For the Lord God is a sun and shield: the Lord will give grace and glory: no good thing will he withhold from them that walk uprightly.
12 O Lord of hosts, blessed is the man that trusteth in thee.
A few quick notes:
Verse 10 – “look upon the face of thine anointed.” Of course, kings were anointed during Old Testament times, but anointings were also performed for others as part of temple ceremonies. (See Exodus 40:12-13, for example.)
Verse 11 – “the Lord God is a sun and shield” – The Savior’s Atonement protects us, “shields” us from the death of the body and the death of the spirit. (See 2 Nephi 9:10) However, the Savior is also the “sun” and his Atonement brings light to our minds and bodies, sanctifying us and making us better people if we will allow Him to do so through our obedience to His commandments and repentance when we fall short of perfect obedience.
Verse 11 – “the Lord will give grace and glory” – Through the Atonement of Christ, we have an opportunity to receive the same glory that He and Heavenly Father have in the Celestial Kingdom. The three kingdoms in which the resurrected live, the Telestial, the Terrestrial and and Celestial are each a kingdom of glory, but the greatest glory resides in the Celestial Kingdom. (See Doctrine and Covenants 88:15-24) However, any glory at all requires a resurrection and that resurrection only comes through Jesus Christ and His Atonement.
Verse 12 – “blessed is the man that trusteth in thee” – As Elder Neal A. Maxwell wrote, “The more we know of Jesus, the more we will love Him. The more we know of Jesus, the more we will trust Him. The more we know of Jesus, the more we will want to be like Him and to be with Him . . . .” See The More We Know of Jesus, the More We Will Love Him