Q: #93. Why did God reject Cain's offering, but accept Abel's?
By: Steve Shirley
A: I believe the offerings of Abel and Cain (Gen 4) are an example of giving worship to God with a right or wrong heart. We can see a difference in their heart attitude by looking at what they offered God. In (Gen 4:3), "Cain brought of the fruit of the ground." However, Abel "brought of the firstlings (firstborn) of his flock (Gen 4:4). Notice, Cain just offered some of his crops, but Abel brought the FIRSTBORN of his flock. The firstborn was very valuable, because it showed dependence on God. (God later required this in the Bible.)
It should be noted that a grain offering was acceptable to God (Lev 2)(Lev 6:14-23)(Num 7). However, it is also interesting to note that God does make a distinction between just offering grain, and the firstfruits of grain (Lev 2:12,14).
God knows the heart of all people (1 Sam 16:7)(1 Chr 28:9)(1 Kin 8:9)(Acts 1:24). God knew Cain's heart, and it showed in what he offered. However, we can also see what was in his heart by his reaction after God rejected his offering. Cain was "very wroth (angry) and his countenance fell" (Gen 4:5). He was not sorry. He did not ask for forgiveness. He was ANGRY! God then told Cain "If thou doest well, shalt thou not be accepted?" (Gen 4:7). Cain wasn't interested in changing (doeth well) though.
I should add here, that some scholars who I respect, believe that the reason God rejected Cain's sacrifice was because it wasn't a blood sacrifice, while Abel's was. Blood sacrifice was for sin, grain offerings were not. Several of these scholars believe that God must have made them aware of the need for blood sacrifice, and Abel obeyed, but Cain did not. I don't deny that this is a possible explanation, but to do this, you must make the Bible say what it doesn't say to fit your reasoning.
Finally, one other theory is simply that Cain offered his works, while Abel did not. A picture of grace vs works.