Rom 14:5.6.
One person esteems one day above another; another esteems every day alike. Let each be fully convinced in his own mind. He who observes the day, observes it to the Lord; and he who does not observe the day, to the Lord he does not observe it.
Theologians and churches say by using this text, the Bible says we do not have to keep a holy day like the Sabbath, because all days are equal.
So does it matter if we keep a holy day like the Sabbath or even a Sunday?
First of all, the text does not say anything about keeping a holy day like the Sabbath as a rest day.
Therefore, to find out what the day the text is talking about, we have to ask ourselves what is the chapter talking about. What is the subject of the chapter? Can one find anything in the chapter that refers to a holy day? What is Paul talking about when referring to every day is alike?
What is the chapter talking about? What is the subject?
Verse 1. Refers to one who is weak in the faith.
Verse 2. The weak one only eats vegetables and others eat all things.
Verse 3.4. Do not judge each other in relation to what one eats.
Verse 5. One person esteems one day above another.
Verse 6. He who eats, eats to the Lord, for he gives God thanks; and he who does not eat, to the Lord he does not eat, and gives God thanks.
Verse 10. We should not judge one another. It is Christ who shall judge us all.
Verse 14. There is nothing unclean in itself. But to him who considers anything to be unclean, to him it is unclean.
Verse 15. Do not destroy with your food the one for whom Christ died.
Verse 17. For the kingdom of God is not eating and drinking, but righteousness and peace and joy in the Holy Spirit.
Verse 20. Do not destroy the work of God for the sake of food.
Verse 21. It is good neither to eat meat nor drink wine nor do anything by which your brother stumbles or is offended or is made weak.
Verse 22. Happy is he who does not condemn himself in what he approves.
Verse 23. But he who doubts is condemned if he eats.
The word “eat” is named 12 times.
The word “judge” is named 7 times.
The word “day” is named 3 times.
The subject of the chapter is not days, but the eating of food and judging one another. Some eat only vegetables and others eat meat. The problem we have here is similar to what Paul was dealing with in (1 Cor 8:). Some members of the church had bought meat from the market place at a cheaper price because it was offered to the gods of the gentiles and they ate it. Others would not eat it, but ate only vegetables. When Paul talks about days in Verse 5.6. he is talking about some members eating on specific days and others did not. The point is one should not judge each other in relation to eating food and fasting. Some Jews fasted twice a week, on Monday and Thursday e.g. Luk 18,12.
Conclusion
There is nothing mentioned in the chapter about worshipping on a holy day. This argument which churches use, is a figment of the imagination and has nothing to do with Bible study.