Lets think about that for a minute. What if I choose to esteem Tuesday for sacred assembly and you choose to esteem Thursday but the Pastor chooses to esteem Wednesday for sacred assembly. Where is the unity? Where is the ability to enjoy the gifts that God has given to each of us to edify His body, the church? The discussion in Romans 14 was not about the seventh day of creation, but rather, it was about doubtful things. Doubtful things are things that are not clearly commanded by God.
Romans 14:1 Receive one who is weak in the faith, but not to disputes over doubtful things.
The seventh day Sabbath is not a doubtful thing. The discussion in Romans 14 was about eating or not eating, which was rooted in the opinions of men, not God. The discussion in Romans was not about the Sabbath, but rather, it was about special days esteemed by man for fasting.
Romans 14:5-6 One man esteems one day above another; another man 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. 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.
One man would esteem one day for fasting above another day and another man would consider everyday alike. There were many disputes in the early church about when to fast. Which day to fast is based on opinions because there was no command given by God so that left it open for debate and personal choice.
Matthew 9:14 Then the disciples of John came to Him, saying, Why do we and the Pharisees fast often, but Your disciples do not fast?
Mark 2:18 The disciples of John and of the Pharisees were fasting. Then they came and said to Him, Why do the disciples of John and of the Pharisees fast, but Your disciples do not fast?
God gives no command as to which day to fast or not to fast. Paul says he who chooses to fast let him be fully convinced in his own mind as to which day he chooses.