As far as I am aware the SDA are the only ones who talk about a sanctuary in heaven
Indeed SDAs are focused on what the Bible calls the "
MAIN POINT" - and most other Christian groups miss it entirely! Glad you noticed this detail which is most often one of the "blind spots" for other Christian denominations.
Heb 8
8
Now the main point in what has been said is this: we have such
a high priest, who has taken His seat at the right hand of the throne of the Majesty in the heavens, 2 a minister in the sanctuary and in
the true tabernacle, which the Lord pitched, not man. 3 For every high priest is appointed to offer both gifts and sacrifices; so it is necessary that this
high priest also have something to offer. 4 Now if He were on earth, He would not be a priest at all, since there are those who offer the gifts according to the Law; 5
who serve a copy and shadow of the heavenly things, just as Moses was warned
by God when he was about to erect the tabernacle; for, “See,” He says, “that you make all things according to the pattern which was shown you on the mountain.” 6 But now
He has obtained a more excellent ministry, by as much as He is also the mediator of a better covenant, which has been enacted on better promises.
A New Covenant
7 For if that first
covenant had been faultless, there would have been no occasion sought for a second.
8 For finding fault with them,
He says,
“Behold, days are coming, says the Lord,
When
I will effect a new covenant
With the house of
Israel and with the house of Judah;
9 Not like the covenant which I made with their fathers
On the day when I took them by the hand
To lead them out of the land of Egypt;
For they did not continue in My covenant,
And I did not care for them, says the Lord.
10 “For t
his is the covenant that I will make with the house of Israel
After those days, says the Lord:
I will put My laws into their minds,
And I will write them on their hearts.
And I will be their God,
And they shall be My people.
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Sadly by "ignoring the main point" about Christ's high priestly ministry in the heavenly sanctuary (as even you admit you are doing) - the result is to miss the key features of the NEW Covenant and the context in which it is implemented.
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Hebrews 9
Now even the first
covenant had regulations of divine worship and the earthly sanctuary. 2 For there was a tabernacle prepared, the outer one, in which
were the lampstand and the table and the sacred bread; this is called the holy place. 3 Behind the second veil there was a tabernacle which is called the Holy of Holies, 4 having a golden altar of incense and the ark of the covenant covered on all sides with gold, in which was a golden jar holding the manna, and Aaron’s rod which budded, and the tables of the covenant;
...
11
But when Christ appeared as a high priest of the good things to come,
He entered through the greater and more perfect tabernacle, not made with hands, that is to say, not of this creation; 12 and not through the blood of goats and calves, but through His own blood, He
entered the holy place once for all, having obtained eternal redemption. 13 For if the blood of goats and bulls and the ashes of a heifer sprinkling those who have been defiled sanctify for the cleansing of the flesh, 14 how much more will the blood of Christ, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?
15
For this reason He is the mediator of a new covenant, so that, since a death has taken place for the redemption of the transgressions that were
committed under the first covenant, those who have been called may receive the promise of the eternal inheritance. 16 For where a covenant is, there must of necessity be the death of the one who made it. 17 For a covenant is valid
only when men are dead, for it is never in force while the one who made it lives. 18 Therefore even
the first covenant was not inaugurated without blood. 19 For when every commandment had been spoken by Moses to all the people according to the Law, he took the blood of the calves and the goats, with water and scarlet wool and hyssop, and sprinkled both the book itself and all the people, 20 saying, “This is the blood of the covenant which God commanded you.” 21 And in the same way he sprinkled both the tabernacle and all the vessels of the ministry with the blood. 22 And according to the Law,
one may almost
say, all things are cleansed with blood, and without shedding of blood there is no forgiveness.
23
Therefore it was necessary for the copies of the things in the heavens to be cleansed with these,
but the heavenly things themselves with better sacrifices than these. 24
For Christ did not enter a holy place made with hands, a mere copy of
the true one, but into heaven itself, now to appear in the presence of God for us; 25
nor was it that He would offer Himself often, as the high priest enters the holy place year by year with blood that is not his own 26
Otherwise, He would have needed to suffer often since the foundation of the world;
but now once at the consummation of the ages He has been manifested to put away sin by the sacrifice of Himself. 27 And inasmuch as it is
appointed for men to die once and after this
comes judgment, 28 so
Christ also, having been offered once to
bear the sins of many, will appear a second time for salvation
without reference to sin, to those who eagerly await Him.
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The entire Hebrews 8-10 sequence is a "blind spot" for those who refuse to study God's Heavenly Sanctuary. And so they miss the full Bible teaching on the New Covenant.