"And in the process of time it came to pass that Cain brought an offering of the fruit of the ground to the Lord. Abel also brought of the firstborn of his flock and of their fat. And the Lord respected Abel and his offering, but He did not respect Cain and his offering. And Cain was very angry, and his countenance fell" (Gen. 4:3-5).
God was very concerned, as we see throughout the Old Testament, with the heart attitude of the person who brought a sacrifice to the altar. Very often in the Old Testament era, people simply went through the motions, offering their sacrifices in a casual, careless, halfhearted, mechanical way, for which they were hypocrites. God said, "I hate, I despise your religious festivals; your assemblies are a stench to me. Even though you bring me burnt offerings and grain offerings, I will not accept them. Though you bring choice fellowship offerings, I will have no regard for them. Away with the noise of your songs! I will not listen to the music of your harps. But let justice roll on like a river, righteousness like a never-failing stream!" (Amos 5:21-24).
God was displeased by the faithlessness of the people as they went through their religious practices. Yet that happens in every generation. People go to church every Sunday and go through the motions of religion while their hearts are far from God. They act out their religion, as actors in a play, but without faith, without any real personal commitment to God.
God is no different today than He was then. Do we render spirit and truth worship unto God as He requires (John 4:24)? What will our worship be like this coming Lord's day? Will we offer a Cain or Abel worship?