There has been a lot has been said about the Bible Sabbath over the years. Some believe that it is the "Seventh Day" and others believe that it is now the First Day. Allow me to begin here: In the New Testament, there are well over 80+ references to the Seventh-Day Sabbath and only 8 references to the First Day of the week. In Acts chapter 18 alone, which was approximately 21 years AFTER the resurrection, you can find the day that Paul was accustomed to keeping holy eluded to 78 times! (see verses 4 & 11 and chapter 17:2 for Paul's customary day of worship).
In regard to the First-Day texts, here they are--Matthew 28:1 // Luke 23:50-56 through 24:1-3 // Mark 16:1-4 // Mark 16:9-11 // John 20:1 // John 20:19 // 1 Corinthians 16:1-3 // Acts 20:7-11. These are the ONLY references to the First-Day of the week. None of which have a commend for a change of the Holy Day, a command for worship, or anything of the sort.
Mark wrote his gospel anywhere from 10-30 years after the cross and mentions not a thing about any change. John's gospel was written about 60 years after Jesus was resurrected and was also silent about any sort of "Holy Day" change. He simply tells of the same event as the other gospel writers. If you notice, Mark 16:1-4 actually refers to both Marys waiting until the Sabbath had past to go anoint Jesus on the First-Day of the week.
Now, in reference to the other two verse sections, 1 Corinthians 16:1-3 & Acts 20:7-11, many different ideas are out there for what these verses really mean. Honestly, the truth is in the texts! In 1 Corinthians 16:1-3, some would say this is an offering being taken at a Sunday (First-Day) morning church service. But the text doesn’t say that. Notice this was an offering “for the saints” and not “of the saints.” Also take note that they were to “lay by him in store.” The actual Greek language reads, “Let each one of you put on one side and store up at home” (Weymouth); “store it up” (ESV); “put aside and save” (NASB). This was not a command to take offerings at church, but to store an offering up at home on Sunday. In other words, Paul was saying to store up an offering FIRST in the beginning of the week so when I (Paul) come, it will be ready for me to take with me. Why store up? 9. Read Acts 11:27-29. There was “great dearth”, or “famine” in Jerusalem. The disciples sent relief to help their “brethren” in Judaea. Also read Romans 15:25-28. This was a relief offering taken to help the Christians in Jerusalem who were experiencing a famine.
Now to Acts 20:7-11. This verse is one that some point to as evidence the disciples were worshiping on Sunday since they were "breaking bread and preaching". Let’s notice several things about this text.
First, preaching and breaking bread DOES NOT make a day holy. I, personally, have broken bread and listened to preaching on almost every day of the week. Breaking bread doesn’t mean they were celebrating a "communion service" at church. Look at Acts 2:46. They broke bread everyday and not just Sunday! In Acts 27:33-35, Paul broke bread with unbelievers. It meant they were simply eating together.
Secondly, this event actually takes place on Saturday night and not Sunday morning as many suppose. Notice Paul preached until midnight, there were "many lights" (it was dark outside), Eutychus fell asleep (it was late at night), and Paul preached until the "break of day" and then went on a trip. That is most likely why they were have food... to celebrate a possible last moment with Paul before he went on his journey.
Also, this was definitely the dark part of the first day of the week. Which would’ve actually been Saturday night (Genesis. 1:5, 8, "and Evening and Morning were the first day."). Paul preached Saturday night and left Sunday morning on a journey. He didn’t go to church on Sunday morning! This actually disproves Sunday keeping since Paul goes on a long journey on Sunday morning and doesn’t "keep it holy".
The Seventh-Day Sabbath was made Holy by God Himself in the creation week. He Rested, be Blessed it, and He Sanctified the Seventh-Day in the beginning. In Malachi 3:6 and Hebrews 13:8, the Bible says that God "does not change". Jesus Says "if you love Me, keep My commandments". In Isaiah 66:22 & 23, the LORD tells us that we will be worshiping Him "from one Sabbath to another" in heaven! It was also Jesus custom to worship, go to church, on the Seventh-Day Sabbath (Luke 4:16).
The Sabbath of the Bible was also given way before the first "Jew" existed. Refer to Exodus 16:25-30 to see that the Commandments of God and His Sabbath existed BEFORE Sinai.
So, if it was made Holy at the beginning, it was kept all throughout the Old Testament, Jesus kept it Holy, Paul kept it Holy, the Gentile converts kept it Holy, and the Lord says that we will worship Him on the Sabbath in Heaven, don't you think it is important to keep the Seventh-Day Holy now? After all, it is the 4th Commandment.
Finally, "Judaizing" is something that does not concern a Bible Christian. It was a phrase that originated in the council of Laodicea. It concerns the Roman church. If you want to be strictly a bible Christian, Jesus again says, "If you love Me, keep My commandments." That definitely includes His "Sign" of sanctification between Him and His people (Ezekiel 20:12).