Why does the first day of the week matter to Christians if Sunday is named after a pagan sun god?
The first day of the week matters because it was the day of the resurrection, not because of its pagan name. Paul instructed believers to lay by in store on that day, giving as God has prospered them, not under a mandated ten percent.
Les teaches that while pagans may have named the first day of the week after the sun god, that does not determine its importance for Christians. The significance is not the day's name but that it was the day of the resurrection. He points to 1 Corinthians 16, where Paul, writing about the collection for the Jerusalem saints, gives order to the churches of Galatia and says that upon the first day of the week, let every one of you lay by him in store. Les connects this to resurrection day. He also notes that giving is not to be mandated as a strict ten percent, though ten percent is a guideline; rather, believers give as the Lord has prospered them, led by free conscience and the Holy Spirit.