(Updated 30 March 2015)
The contrast is not between an offering of plant life and an offering of animal life, but between a careless, thoughtless offering and a choice, generous offering (cf. Lev 3:16). Motivation and heart attitude are all-important, and God looked with favor on Abel and his offering because of Abel’s faith (Heb 11:4).(3)
By faith in this atonement or plan of redemption, Abel offered to God a sacrifice that was accepted, which was the firstlings of the flock. Cain offered of the fruit of the ground, and was not accepted, because he could not do it in faith, he could have no faith, or could not exercise faith contrary to the plan of heaven. It must be shedding the blood of the Only Begotten to atone for man; for this was the plan of redemption; and without the shedding of blood was no remission; and as the sacrifice was instituted for a type, by which man was to discern the great Sacrifice which God had prepared; to offer a sacrifice contrary to that, no faith could be exercised, because redemption was not purchased in that way, nor the power of atonement instituted after that order; consequently Cain could have no faith; and whatsoever is not of faith, is sin. But Abel offered an acceptable sacrifice, by which he obtained witness that he was righteous, God Himself testifying of his gifts. Certainly, the shedding of the blood of a beast could be beneficial to no man, except it was done in imitation, or as a type, or explanation of what was to be offered through the gift of God Himself; and this performance done with an eye looking forward in faith on the power of that great Sacrifice for a remission of sins. But however various may have been, and may be at the present time, the opinions of men respecting the conduct of Abel, and the knowledge which he had on the subject of atonement, it is evident in our minds, that he was instructed more fully in the plan than what the Bible speaks of, for how could he offer a sacrifice in faith, looking to God for a remission of his sins in the power of the great atonement, without having been previously instructed in that plan? And further, if he was accepted of God, what were the ordinances performed further than the offering of the firstlings of the flock?(5)
2. This is consistent with Jesus' teaching, "Search the scriptures; for ... they are they which testify of me." (John 5:39.) It is not always remembered that the "scriptures" he speaks of were the Old Testament. Perhaps a few things may have been circulating from his teachings. There are a number of ways one can approach this idea. An interesting one is found in an article in the Ensign asserting that the Book of Mormon mentions the Savior more times per verse than even the New Testament. See, Susan Ward Easton, "Discovery," Ensign, (July 1978), p. 60.
3. Kenneth Barker, ed, The NIV Study Bible: New International Version, (Grand Rapids: Zondervan, 1985), p. 11, note at Gen. 4:3-4.
4. Joseph Smith, “The Elders of The Church in Kirtland, To Their Brethren Abroad,” HC 2:15-16. See also TPJS, pp. 58-59, emphasis added. The original was in the Evening and Morning Star, vol. 2, no. 18 (March 1834), 142-144; no. 19 (April 1834), p. 152. Respecting Joseph's argument that Abel knew the gospel and the law of sacrifice relative to the death of Christ, Moses 5:7 teaches us that an angel taught Adam that animal sacrifice “is a similitude of the sacrifice of the Only Begotten of the Father....” Surely Adam taught this to his children. Moses 5:12 says Adam and Eve "made all things known unto their sons and their daughters." Concerning Moses 5:7, Elder M. Russell Ballard has written, much as Joseph argued about Abel, “This teaches us that originally, ancient Israel understood the relationship between the sacrifice of their offerings and the sacrifice of the Lamb of God.” He refers the reader to D&C 138:12-13, which says: “And there were gathered together in one place an innumerable company of the spirits of the just, who had been faithful in the testimony of Jesus while they lived in mortality; and who had offered sacrifice in the similitude of the great sacrifice of the Son of God, and had suffered tribulation in their Redeemer’s name.” See M. Russell Ballard, Yesterday, Today, and Forever: Timeless Gospel Messages with Insights from his Grandfathers Melvin J. Ballard and Hyrum Mack Smith, Salt Lake City: Deseret Book, 2015, p. 118.
5. Joseph Smith had more to say in this same epistle about blood sacrifice and their knowledge of Christ. He wrote: "Our friends may say, perhaps, that there were never any ordinances except those of offering sacrifices before the coming of Christ, and that it could not be possible before the Gospel to have been administered while the law of sacrifices of blood was in force. But we will recollect that Abraham offered sacrifice, and notwithstanding this, had the Gospel preached to him. That the offering of sacrifice was only to point the mind forward to Christ, we infer from these remarkable words of Jesus to the Jews: "Your Father Abraham rejoiced to see my day: and he saw it, and was glad" (John 8:56). So, then, because the ancients offered sacrifice it did not hinder their hearing the Gospel; but served, as we said before, to open their eyes, and enable them to look forward to the time of the coming of the Savior, and rejoice in His redemption. We find also, that when the Israelites came out of Egypt they had the Gospel preached to them, according to Paul in his letter to the Hebrews, which says: "For unto us was the Gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it" (see Heb. 4:2). It is said again, in Gal. 3:19, that the law (of Moses, or the Levitical law) was "added" because of transgression. What, we ask, was this law added to, if it was not added to the Gospel? It must be plain that it was added to the Gospel, since we learn that they had the Gospel preached to them. From these few facts, we conclude that whenever the Lord revealed Himself to men in ancient days, and commanded them to offer sacrifice to Him, that it was done that they might look forward in faith to the time of His coming, and rely upon the power of that atonement for a remission of their sins. And this they have done, thousands who have gone before us, whose garments are spotless, and who are, like Job, waiting with an assurance like his, that they will see Him in the latter day upon the earth, even in their flesh." HC 2:16-17, TPJS, 60-61, emphasis added.