Romans 14:5-6 - Sabbath or Feast Days
Many have concluded that this verse implies we no longer need to keep the fourth Commandment being the Lord's Sabbath. But where in the entire chapter does it give any such indication that the fourth Commandment is being referred to? The fact is that Romans chapter 14 does not even use the word Sabbath and is typically a chosen assumption from those trying to avoid spending special one on one time with their Creator on His holy day.
Another very relevant fact is that the word “alike” is not actually in the Greek text at all and was added by the translators which has tended to imply something that Paul never intended.
So keeping true to the original Greek text, this is what Paul really said in verse 5.
Romans 14:5 “One man esteemeth one day above another: another esteemeth every day. Let every man be fully persuaded in his own mind.”
The passage context reveals that Romans 14:5 refers to the Jewish institutions and especially their festivals such as the Passover, Day of Atonement, the new moons etc, and meat sacrificed to idols. The Bible never refers to the Lord's Sabbath as just a day. It is always called The Sabbath or Sabbath Day.
Some Jews who did not yet know or understand the Gospel message thought these days still had to be observed while the Gentile Christian not having ever kept these feast days knew they were under no obligation to keep them. Consequently there was disagreement between Jews and Gentiles over keeping these sacrificial feasts that ended at the cross.
So Paul is instructing them to consider those whose faith enables them to immediately to leave behind all ceremonial holidays and not to despise others whose faith is not as strong. And also for the latter to not criticize those who seem to them to be more lax but are not as they understand they are under no obligation to keep these Jewish feast days that were instituted because of sin and hence why they ended at the cross.
This is what caused the enmity between Jew and Gentiles before the cross that Paul spoke of in Ephesians 2:15 “Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace.” Albert Barnes' notes on the Bible explains this verse and issue well. See Ephesians 2:15 for more detail on this verse.
There is now a growing group of Churches that came from the collapse of the Herbert Armstrong movement that insists that we still need to observe the feast days without the sacrifices that were in the Mosaic Law that ended but scripture shows this movement is in error. See do we need to keep the feast days for very detailed information.
See Adam Clarke and Albert Barnes Bible Commentaries and Romans 14:5-6 for a detailed exegesis on this verse.