Matt 24:24-26 (KJV) – For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect. Behold, I have told you before. Wherefore if they shall say unto you, Behold, he is in the desert; go not forth: behold, he is in the secret chambers; believe it not.
Warning: Adventist admission:
“To say Christ entered the Holy of Holies, the tenth of the seventh month, is saying He is in the secret chamber.”
– Day Star, Vol 7 no 12-13, 11 Oct 1845; see Vol 7 page 51, letter by ORL Crosier, one of the Adventist/Millerite inventors of the claim that Jesus entered the Holy of Holies in 1844. [emphasis mine]
Adventism teaches that Christ entered the Holy of Holies in 1844, and that he is still there to this day.
This teaching is an Adventist invention allowing them to pretend that their 1844 prophecies were still valid. Jesus failed to return in 1844. Their prophecies were proven false. So they claimed that he was in the secret chambers, and his entry was what really happened in 1844.
Jesus said false Christs and false prophets would make that claim. The secret chamber refers to the veiled innermost chamber of the tabernacle, the Holy of Holies. Jesus entered this shortly after he died (Hebrews 6:19) and later sat down at the Father’s right hand (Hebrews 1:3), symbolising completion of his task. There is no further entry into this place needed. Those who claim Jesus is there, contradict both Paul and Jesus.

Image source: Lying For God website, used with permission
Psalms 91:1 (KJV) – He that dwelleth in the secret place of the most High shall abide under the shadow of the Almighty.
Psalms 27:5 (KJV) – For in the time of trouble he shall hide me in his pavilion: in the secret of his tabernacle shall he hide me; he shall set me up upon a rock.
Ezekiel 7:22 (KJV) – My face will I turn also from them, and they shall pollute my secret place: for the robbers shall enter into it, and defile it.