This quote is from the Lectures on Systematic Theology (the specific lecture is available in this pdf) of Robert Lewis Dabney, one of the two best-known theologians from the old Southern Presbyterian Church. In this passage, he was stating his opinion that a lack of Sabbath concern in European churches, including both Calvin and Luther personally, was the reason that the European mainland was, even in his time, a spiritual wasteland. I am sure that, if he lived in our day, he would suggest that the same disease is what has destroyed the Protestant churches, his own Presbyterian Church included, have faded into paganism, even in the English-speaking nations.
The view Dabney was defending can be found in the Westminster Larger Catechism, Question 116: "What is required in the fourth commandment? Answer: The fourth commandment requires of all men the sanctifying or keeping holy to God such set times as He has appointed in His Word, expressly one whole day in seven; which was the seventh from the beginning of the world to the resurrection of Christ, and the first day of the week ever since, and so to continue to the end of the world; which is the Christian sabbath, and in the New Testament called the Lord's day." (See also Questions 117-121). He held, and I also hold, that this view best summarizes the biblical teaching relevant to the Lord's Day, or Sabbath, for the Christian.
The opening biblical reference is Genesis 2:1-3: "Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God finished His work that He had done, and He rested on the seventh day from all His work that He had done. So God blessed the seventh day and made it holy, because on it God rested from all His work that He had done in creation." That is, the Sabbath arises from the creative acts of God at the beginning of history. Remember that; it is a crucial aspect of what I am advocating.
Next, it comes up in the IVth Commandment, in both Exodus 20:8-11 and Deuteronomy 5:12-15.
The objections to continuing Sabbath observance, even in its Christian first-day form, are twofold. The first is a general objection that the ceremonial law has been fulfilled in Christ, and is therefore no longer binding on the Christian. That principle is certainly correct. However, it is irrelevant here, because, as I mentioned above, the Sabbath is a creation ordinance, instituted thousands of years - at least- before the time of Moses. In addition, we have the New Testament concurring in Hebrews 4:9, "There remains a Sabbath rest for the people of God." Thus, the Sabbath is found both before the ceremonial law was given and after it was abrogated in Christ. Therefore, it could not have been abolished with the ceremonies, such as the sacrifices and the Levitical priesthood.
The other objection is more specific. It is based on Colossians 2:16, "Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day." But that interpretation is only possible if you ignore the next verse, "These are a shadow of the things to come, but the substance belongs to Christ." This brings us back to the exact point I made in the paragraph above. Paul is encouraging the Colossian believers not to be shaken by the criticisms of the Jews, or of Judaizers in the Church, who advocated the continuing devotion to the Jewish ceremonies, e.g., the festivals and seventh-day Sabbath attendance at synagogue or the Temple. In other words, he is not referring to the Sabbath principle here, but rather to the now-superseded Jewish Sabbath. Otherwise, Paul's companion Luke would have been remiss in recording that the Christians met on the first day of the week (Acts 20:7). And Paul himself would have erred in encouraging the believers to take up an offering in their meetings on that day (I Corinthians 16:2). So, the general reading of Sabbath in Colossians 2:16 would make it contradict these two verses, and especially Hebrews 4:9 (quoted above). The narrow reading, i.e., that it is reference specifically to the Jewish Sabbath, must therefore be the correct interpretation.