The sabbath day is commanded to be lifted up, as described in the 4th commandment. The other days of the week belong to God just like the Sabbath, but none of them have any exceptional value when compared to the sabbath day-there is a vast difference. Part of the problem today is people devalue the sabbath day. In that, they look for other days to increase value in, i.e. Christmas, Easter, birthdays, etc. etc. etc.
“The observance of the uncommanded holy-days is ever found to interfere with the due sanctification of the Lord’s-day. Adding to the appointments of God is superstition; and superstition has ever been found unfriendly to genuine obedience. Its [adherents], like the Jews of old, have ever been found more tenacious of their own inventions, of traditionary dreams, than of God’s revealed code of duty. Accordingly, there is perhaps no fact more universal and unquestionable, than that the zealous observers of stated fasts and festivals are characteristically lax in the observance of that one day which God has eminently set apart for himself, and on the sanctification of which all the vital interests of practical religion are suspended.”
– Samuel Miller, “Presbyterianism the Truly Primitive and Apostolic Constitution of the Church of Christ.