Joe Crews' sermon, "Is Sunday Really Sacred?", is a foundational study from his "Library of Sermons" that challenges the common Christian practice of Sunday worship. The central theme of the sermon is a deep dive into the biblical and historical evidence regarding the day of worship.

The main points of the sermon include:

• A Call to Sincerity: Crews begins by emphasizing the importance of seeking truth directly from the Bible, rather than relying on tradition or popular opinion. He uses an analogy of getting lost while driving to illustrate that sincerity in believing you are on the right path doesn't make it true if the path is wrong.

• The Sabbath of the Old Testament: The sermon establishes that the fourth commandment in the Old Testament explicitly commands the observance of the seventh day, Saturday, as the Sabbath.

• Examining New Testament Texts: Crews then meticulously examines all biblical texts that mention the first day of the week (Sunday), to determine if they establish a new sacred day. He addresses common arguments, such as the resurrection of Jesus on a Sunday, the day of Pentecost, and specific gatherings mentioned in the book of Acts, and concludes that none of these passages command or even suggest that Sunday replaced the Sabbath as the day of worship.

• Historical Shift: The sermon explores the historical reasons for the shift from Sabbath observance to Sunday worship, arguing that this change was not based on a biblical mandate but rather on human tradition and the influence of the Roman Catholic Church.

• The Importance of the Sabbath: Ultimately, the sermon argues that the biblical Sabbath, the seventh day, remains God's ordained day of rest and worship for Christians, and that observing Sunday is a departure from God's explicit command. The core message is a call to align one's practice with the clear teachings of Scripture rather than with religious custom.