Why did the smoke of the incense cover the holy place?
The smoke of the incense covered that inner room to obliterate the very presence of God from even the high priest, veiling the divine presence as he ministered. It also pictured Christ’s finished work, and Revelation identifies the incense as the prayers of the saints.
Les explains that on the Day of Atonement especially, the high priest took coals from the brazen altar and carried them into the little altar inside. He did not burn animal fat there; he burned incense. The smoke would literally, you might say, obliterate the very presence of God from even the high priest, and it would just cover that little room. Les ties all of this to Christ’s finished work. He also notes that the book of Revelation tells us the sweet odor of the incense is in reality the prayers of the saints, so believers are involved in that as well.