Does the Bible teach that Sunday is a special holy day above the other days of the week?
No. Paul writes in Romans 13 not to regard one day higher than another but to regard every day alike. Even Sunday is not taught in Scripture as a special holy day above the other six days. Every day is alike for the believer, who serves God just as much Monday through Sunday.
Les explains 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. Paul says in Romans 13, “Don’t regard one day higher than another… Regard every day alike.” Les has nothing against Sunday per se, but even Sunday is not taught in Scripture as we understand Sunday. Paul merely said that when believers come together and bring their offerings, it can be on the first day of the week, resurrection day. But setting Sunday up as a special holy day above the other six days is not taught. Every day is alike for the believer; we are to serve God as much Monday through Friday as Saturday and Sunday. This has all been nailed to His cross. In Galatians 4, 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 appeals because people like to satisfy their ego.