Are all days alike for the believer, or is one day more for serving God?
Paul instructs believers not to regard one day higher than another, but to regard every day alike. Sunday is not set up as a special holy day above the other six; every day is alike for the believer, and we serve God Monday through Friday just as on Saturday and Sunday.
Les teaches that the book says nothing about practicing a system of worship in this age of grace. Christ nailed all that to His cross, and believers are now free. In the passage cited, Paul says not to regard one day higher than another but to regard every day alike. Les notes he has nothing against Sunday, but even Sunday is not taught in Scripture as we understand it. Paul merely said that when they came together to bring offerings, it was on the first day of the week, resurrection day. That does not set Sunday up as a special holy day above the other six. Every day is alike for the believer, and we are to serve God just as much Monday through Friday as Saturday and Sunday. This, too, has been nailed to His cross. Les also connects this to Galatians, where Paul wrote because Judaizers were convincing Gentiles they had to keep the Law to experience salvation, and he admonished them not to become legalists. Legalism still appears today because people like to satisfy their own ego, but God will have none of it.