The Lord's Ordinance and Foot Washing are ceremonial feasts. We also by tradition observe Camp Meetings,
which are simile of the Feast of Tabernacles, but much of this observance is reduced to formality and thus not what the feast keeping was originally designed for by God.
Chomsky said "However, I think most, if not all, Adventists, agree that it is impossible to keep the Sabbath as described in the Old Testament."
Rob" I doubt that. The Sabbath "ceasing day" is a part of the faith principles in the Ten Commandments, so observing the faith principle is by asking God through faith. And a Divine Power flows, what is impossible in asking for Divine help?
The problem is we assume we do things using human power, which is a myth and something that means nothing to the Lord.
Imagine if God ceased to empower biological decisions for a few seconds, but empowered biological creatures to remain living; and Satan was also no allowed to automatically empower "Self" powers into the human like He does, could the humans steeped into doing things dysfunctionally, continue to do things, as a biological agent? The answer is no.
Once the human agent's nature wishes to sin dysfunctionally, the human agent cannot with a provider of some sort providing.
This is the reason why the Devil is termed a "provider" : (I translate the verse with Hebrew intent)
Joh 8:44 Ye are of your "provider" the devil, and the lusts of your "provider" ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the "provider" of it.
And confirmation from our prophet my findings are correct?
Guard carefully your own heart, lest you become selfish and covetous, and you weave into the web the threads that Satan provides, threads of the same kind as those that form the texture of his own character. . {Ms 50, 1903, par. 8}
So asking God for Divine Help, even on Sabbath, is easy. Ask and it shall be given you the Bible says.
Shalom