Worship and the glory of God are closely connected in Scripture (Lev. 10:1–3; Heb. 12:18–29), which means that we must pay close attention to how we structure worship and what we do in worship if we want to glorify and please God. Contrary to the widespread cultural assumption that people may worship the Creator "as they conceive of Him" or that God is pleased with whatever worship is offered to Him, there are forms of "worship" that are displeasing to Him.
Today's passage reveals this truth to us, explaining that when Cain and Abel offered worship to the Lord, God had regard only "for Abel and his offering" (Gen. 4:1–5). Something about Cain's sacrifice of worship displeased the Lord, and it was not the fact that Cain offered a bloodless offering. God actually commanded His people to bring Him grain offerings (Lev. 2), so there was a manner in which Cain could have sacrificed His produce that would have been pleasing to the Lord. The problem with Cain's sacrifice was that His heart was not in the offering. Abel brought the "firstborn of his flock" and "their fat portions," giving the very best to God and trusting that the Lord would provide other sheep to meet his needs (Gen. 4:4). Cain, on the other hand, treated worship as an afterthought. The contrast of Cain's sacrifice with Abel's offering indicates that instead of bringing the Lord the first and the best, Cain sacrificed what was left over after He had taken "his share" (v. 3).
If worship can displease our Creator, the application for us is easy. We must search our hearts and our worship practices to make sure that they are not displeasing to the Lord. Should we find that our worship fails to please God, we must change it.
Jesus taught the most basic principle for worship—"God is spirit, and those who worship him must worship in spirit and truth" (John 4:24). Cain did not worship the Lord in spirit, for his heart was not in it, and so our Creator did not accept His offering. Yet zeal of the heart is not sufficient to make our praise pleasing in God's sight. One of the most enthusiastic worship services in history was the worship of the golden calf, and that did not end well for the worshipers (Ex. 32). Praise from the heart is not enough to please the Lord if we are not worshiping the true God, and so we must prize truth alongside ardor when we praise our Creator.
In worship, we may say all the right things in our liturgies, but if our hearts are not in it, the Lord is displeased with our offering of praise. Similarly, our hearts may be fully into worshiping God, but if we entertain falsehood in our worship or praise Him in a manner that is not sanctioned in Scripture, we displease our Creator. We must emphasize both heartfelt praise of our Creator and worship that is structured according to His Word.