First, the word of God does not say that every day is the same--not here, or anywhere else. Divine approval is not given to the position esteeming "every day alike." The point of this passage is that God provides for the conscience of His children, making no allowance for it to be ignored. Believers are encouraged to seek full persuasion concerning their perspective, not allowing it to become a hollow and meaningless position. Somehow, the phrase, "he that regardeth not the day, to the Lord he doth not regard it" is not appealing. It lacks the maturity available in Christ.
Throughout Scripture, God placed significant meaning upon epochal days. Israel remembered the day they came out of Egypt, the day the Law was given, and the day they crossed over into Canaan. However, what has happened on the first day of the week causes those events to pale in insignificance by way of comparison.
Jesus was raised from the dead on the first day of the week (Matt. 28:1-2). He appeared to His disciples twice on the first day of the week (John 20:19, 26). Pentecost occurred on the first day of the week, fifty days after the Passover, and ten days after the ascension. These were all matters involving Deity. Candidly, it is difficult for me to say one day is no better than another when Christ so consistently blessed the first day of the week. Every Gospel writer makes a point of relating Christ's resurrection to "the first day of the week" (Matt. 28:1; Mark 16:2; Luke 24:1; John 20:1). It is absurd to conceive of the Spirit speaking in this manner if there were no significance to the day. If it is true that one day is not more significant than another, He would have employed language like "a certain day" (Lk. 5:17; 8:22), or some other generality.
However, this is not a matter of law, and must not be so viewed. Our associations and involvements with the Living God must be based upon perception and commitment, not obligation. I only bring the matter up in these studies to emphasize the importance of our frame of mind. When we come together, the consideration of Christ's relationship to the first day of the week will affect our use of it. We will appeal to Him to honor us with His presence in a special way, like He did in old time. There is no reason for this day to be like every other day. It can be a mountain top, a spiritual epoch, and a time of unusual blessing.
I have found that those insisting that every day is "the Lord's day" are not generally noted for spiritual productivity and focus every day. In my opinion, our personal makeup requires a time of unmitigated focus to make significant spiritual progress. The first day of the week should be viewed as such a time. In God's kingdom, unusual effort is matched by uncommon blessing. Our Lord will honor those that seek excellent things on the first day of the week. But for those that look at it as "just another day," nothing unusual is likely to happen.