Yes, many God-fearing, up-right people who have followed God to the fullness of their conviction in faith and obedience but never understood or kept the true sabbath, will be saved.
Because so many good Christians have fallen asleep in the triumphs of faith and have not understood or kept the true Sabbath, they, (people who realize which day is God's true Sabbath) are doubting about its being a test for us now in the time of the end..
Several issues here --
One is the sanctuary message and the importance of 1844 when the three angels messages began to sound. This was not just an unnoticed movement. It was a movement that stirred the Christian world. "worship the Creator" :"hour of His judgement is come". "sanctuary to be cleansed" "Christ is coming".
No, the sanctuary was not the earth, and because Christ's second coming didn't cleanse the earth in 1844, the Christian world threw out the whole message. But none of those prophesies said Christ would come in 1844. What were the prophesies saying?
--Restore the worship of the Creator Who made heaven and earth
--The hour of His judgment is come
-- The sanctuary is to be cleansed
-- Christ is coming (we don't know that hour)
Then there was the focus on the third angel of Rev. 14
The wrath of God on those who follow the beast, his image and receive his mark.
God's blessings on those who keep His commandments and have the faith of Jesus.
-- What commandments?
But not one is made to suffer the wrath of God until the truth has been brought home to his mind and conscience, and has been rejected. There are many who have never had an opportunity to hear the special truths for this time. The obligation of the fourth commandment has never been set before them in its true light. He who reads every heart, and tries every motive, will leave none who desire a knowledge of the truth, to be deceived as to the issues of the controversy. The decree is not to be urged upon the people blindly. Every one is to have sufficient light to make his decision intelligently. GC 605
Don't for a moment believe Sabbath observance will atone for the breaking of other commandments. 1 Corinthians 6: 9 Don't you know that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with men, 10 nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God. 11 And such were some of you: but you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus Christ, and in the Spirit of our God.
Likewise we understand -- "Don't you know that those who will not worship the Creator God on the day He sanctified, blessed and placed in the very heart of His commandments can not enter the kingdom of God. And yes, such were some of you, but you were washed and you were sanctified, you were justified in the name of the Lord Jesus..."
When we keep the Sabbath it is a sign that we worship God Who sanctifies us! (Ez. 20:12) It is a sign we are resting in Him!
The light concerning the binding claims of the law of God is to be presented everywhere. This is to be a deciding question. It will test and prove the world.?Special Testimonies, Series A, 7:17, 18. (1874).
It is on the law of God that the last great struggle of the controversy between Christ and His angels and Satan and his angels will come, and it will be decisive for all the world.... Men in responsible positions will not only ignore and despise the Sabbath themselves, but from the sacred desk will urge upon the people the observance of the first day of the week, pleading tradition and custom in behalf of this man-made institution. They will point to calamities on land and sea?to the storms of wind, the floods, the earthquakes, the destruction by fire?as judgments indicating God's displeasure because Sunday is not sacredly observed. These calamities will increase more and more, one disaster will follow close upon the heels of another; and those who make void the law of God will point to the few who are keeping the Sabbath of the fourth commandment as the ones who are bringing wrath upon the world. This falsehood is Satan's device that he may ensnare the unwary.?The Southern Watchman, June 28, 1904.
We can see things building up to this!
After 1844 the Sabbath truth was preached with considerable energy.
How did the Christian world respond?
Every excuse to reject the true Sabbath was brought forth and a mountain of opposition mounted. Even to the preaching that God's holy law was nailed to the cross!
The Christian world has accepted the falsehoods of Satan, and has believed and advocated a change in the fourth commandment, which was given as a commemoration of God's creative power in making the world. This falsehood has been working out its baleful results in making of no effect the whole law, in placing upon the human mind the impression that God is not invariable, invincible truth. This is the cup of intoxication that the Christian world is drinking, with which the inhabitants of the earth are becoming drunken. Satan is seeking to destroy the force of the Ten Commandments, urging his agents to declare that Christ nailed them to his cross. The cross is an immutable argument of the unchangeable character of the law of God. Christ died in order that a way might be provided for saving the sinner, in meeting the demands of the broken law. The law was written with the finger of God upon tables of stone, and John saw the temple of God open in heaven, and in the temple the ark of his covenant....
the prophet describes the scenes of the Gospel age, and he sees in heaven the ark of the testimony. There the holy law of God shines in holy dignity, just as when God wrote it with his own finger on tables of stone.
John describes the work that will be done in the last days, when the Protestant churches form a confederacy with the Catholic power, and work against the law of God and against those who keep his commandments. John says, ?The dragon was wroth with the woman, and went to make war with the remnant of her seed, which keep the commandments of God, and have the testimony of Jesus Christ.?
The Protestant world have cherished an institution of the Papacy,?they have observed Sunday in preference to the Sabbath of the Lord their God,?and in compelling men to keep Sunday, under penalty of law, they are exalting the first day of the week, a spurious sabbath, and casting dishonor upon the Sabbath of the fourth commandment Signs of the Times March 12, 1896.
We can now see how all the storms, earthquakes, floods, fires, etc. can be blamed on lack of Sunday observance (Climate change agenda) with the next step leading to appeasing the gods with Sunday observance -- we are on the thresh hold of that happening.
Heretofore those who presented the truths of the third angel's message have often been regarded as mere alarmists....But as the question of enforcing Sunday observance is widely agitated, the event so long doubted and disbelieved is seen to be approaching, and the third message will produce an effect which it could not have had before.
It is when the Christian world, who have, especially in the last 175 years, vehemently declared that keeping God's true Sabbath is legalism, that it was nailed to the cross and is no longer binding, then turn around and demand, by force of law that everyone observe sunday as the day of rest, that the third angels message becomes very plain.
Every person will be brought to decision.
And every person will worship on either that papal/pagan day of the sun, or on the day God our Creator sanctified and blessed and asked His people to Remember. A sign that He is their God and sanctifier.