The True Sanctuary...

Adventists are ridiculed or brushed aside by many Protestant denominations and the Church of Rome for their teaching on the 2300 days, the heavenly Sanctuary, and the investigative judgment. For their part, many life-long Seventh-day Adventists yawn, sniff, ignore, and deride these teachings with words I cannot write (but have heard, directly and clearly).
Paul writes in Hebrews, a more authoritative source than any church or church member, and essentially grabs us by the collar of our dis-attention when he says: "Now this is the main point of the things we are saying: We have such a High Priest, who is seated at the right hand of the throne of the Majesty in the heavens, a Minister of the sanctuary and of the true tabernacle which the Lord erected, and not man, for every high priest is appointed to offer both gifts and sacrifices. Therefore it is necessary that this One also have something to offer. For if He were on earth, He would not be a priest, since there are priests who offer the gifts according to the law; who serve the copy and shadow of the heavenly things, as Moses was divinely instructed when he was about to build the tabernacle. For he said, 'See that you make all things according to the pattern shown you on the mountain.'" [Hebrews 8:1-5]
Isaiah writes concerning the Christ: "Therefore I will divide Him a portion with the great, and He shall divide the spoil with the strong, because He poured out His soul unto death, and He was numbered with the transgressors, and He bore the sin of many and made intercession for the transgressors" [Isaiah 53:12].
Again Paul writes "Who is he who condemns? It is Christ who died, and furthermore, is also risen, who is even at the right hand of God, who also makes intercession for us" [Romans 8:34]. And in Hebrews; But He, because He continues forever, has an unchangeable priesthood. Therefore He is also able to save to the uttermost those who come to God through Him, since He always lives to make intercession for them [Hebrews 7:24, 25]. Because He (is) "...a priest forever according to the order of Melchizedek" [Hebrews 7:17].
Therefore...those who believe that Christ's work for man was finished on the cross, either have not read (guided by the Holy Spirit) or deny out of hand, the main points the writer makes throughout the book of Hebrews.
If the reader desires to learn more of what Seventh-day Adventists believe about the Heavenly Sanctuary and the powerful Salvific (referencing salvation) symbolism intrinsic in the divinely directed desert Tabernacle constructed under the supervision of Moses. I recommend that you google and then select "Peter Gregory GYC Baltimore 2008 1 of 4".

The speaker is a dynamic Korean-born preacher named Peter Gregory. Whoever chooses to follow this link will learn more about a fundamental Seventh-day Adventist belief than is (very probably or perhaps) known by a majority of contemporary Adventists. Speaking for myself, this is the best, most informative, most spiritual sermon I have heard on the topic of the sanctuary and the 2300 days in 63 years...the years I have been paying attention.
Blessings await you. e.c.