The Mishna Berura - the most widely used halachic code of the 20th century - in his introduction to the laws of Shabbat explains the crucial importance of learning the laws of Shabbat. With all its myriad details it is, he writes, virtually impossible to properly keep Shabbat without a solid understanding of its laws.
These words were written over 100 years ago and I can only imagine what the Chafetz Chaim might write today. Modernity and the technological revolution have added many layers of complexity to the laws of Shabbat. The principle that “an ignoramus cannot be a pious person” (Avot 2:5) is more manifest in the laws of Shabbat which are not only many but occur on a weekly basis.
Shabbat observance in Talmudic times was much easier. The 39 melachot had great relevance for farmers, hunters, tanners and the like. Observing Shabbat basically meant not working - something most of us do in any event. What makes Shabbat observance so complex today is not the actual 39 melachot but their derivatives and applications to modernity. Unlike in Talmudic times, today we can “create” much even without going to work - something that was harder to do in antiquity.
So easy was it to observe Shabbat that the Rambam (Mishne Torah, Shabbat 24:12) writes that the reason the Sages instituted the laws of muktza was to ensure Shabbat be special. One who had no need to work might find it difficult to violate Shabbat and hence Shabbat would be little different than the other days of the week. By instituting the laws of muktza Shabbat was distinguished from the rest of the week. While one may not work it would be very unlikely that one not handle a muktzaitem - and it was the refraining from such that was the sum total of Shabbat observance.
It is only due to the ease of keeping Shabbat that we can understand a surprising line of reasoning in the Gemara. “One who takes a vow [not to benefit] from shovtei Shabbat, those who rest on Shabbat, is forbidden [to derive benefit] from Jews and from Kutim (Nedarim 31a). As in much of Nedarim people say all kinds of (silly) things and our Mishna seems to be no exception. For reasons the Mishna does not even attempt to explain one has forbidden upon themselves benefit from all those who rest on Shabbat i.e. from his fellow Jews. The Mishna teaches that such a vow also includes Kutim, those who converted “out of fear of the lions” and observed some but not all of Jewish law (see Melachim 2, 17:24-42). Shabbat was amongst the laws they did observe and hence they are included in the vow.
What is startling is the Gemara’s immediate question on the Mishna. If the term shovtei Shabbat means those who observe Shabbat why does the Mishna limit the vow to Jews and Kutim? What about idol worshippers who observe Shabbat? To this the Gemara - without batting an eyelash - responds that shovtei Shabbat means not only that they observe Shabbat - something some idol worshippers also did! - but those who are commanded to observe Shabbat, something that excludes idol worshippers. In fact, Jewish law rules that non-Jews are not permitted to keep Shabbat (Sanhedrin 58b). Shabbat is a special treasure between G-d and the Jewish people and one can only enjoy the wonderful gift of Shabbat if one converts to Judaism.
What the Gemara does not explain is why in the world would an idol worshipper keep Shabbat? This is especially strange as our rabbis equate Shabbat observance with acceptance of G-d as Master of the universe and hence those who observe Shabbat are almost by definition not idol worshippers (see Chullin 5a and Rambam Hilchot Shabbat 30:15). Shabbat and idol worship would be a fine definition of an oxymoron. It thus appears that the idol worshipper is observing Shabbat accidentally. He too likes the weekend off and in the simple society of yesteryear he willy-nilly finds himself observing Shabbat. It is only because the term shovtei Shabbat is to be understood as those who are commanded to observe Shabbat that the idol worshiper is not included in this vow.
 Truth be told even if one is expert in the laws of Shabbat, fully observing it - as understood by people even only 10 years ago - is next to impossible. It is just not possible to walk on the street, into an apartment building or even shul without unwittingly triggering some electric activity. And try staying at a hotel for Shabbat. Great halachic authorities have explained why these are not technically a violation of Shabbat but I mention this to explain the complexity of modern life and Shabbat. It is no coincidence that issues like the Shabbat switch have garnered much debate. How Shabbat might look 100 years from now is anyone’s guess but it will surely combine the old and the new.
 On the surface this is a most difficult Rambam. What about Kiddush, davening and the elaborate meals? Surely Shabbat was very different than the rest of the week. Yet all the above are positive actions falling under the rubric of Zachor, of actively observing Shabbat. Apparently we also need to make Shabbat special vis a vis Shamor, refraining from actions on Shabbat.